José A. Cabranes, Circuit Judge:

This petition for enforcement of an order of the National Labor Relations Board (the "Board" or the "NLRB") and an employer's cross-petition for review present two questions. The first is whether the employer, Respondent-Cross-Petitioner Pier Sixty, LLC ("Pier Sixty"), has forfeited its challenge to the legality of the appointment of Acting General Counsel of the NLRB, Lafe Solomon ("Solomon"). Pier Sixty argues that Solomon, who authorized the complaint in this case, served in violation of the Federal Vacancies Reform Act of 1998 (the "FVRA")1 and that the complaint was therefore issued illegally. Although Pier Sixty failed to raise this argument before the Board, as required by Section 10(e) of the National Labor Relations Act (the "NLRA"),2 Pier Sixty argues that we may nonetheless consider it on appeal, under the "extraordinary circumstances" exception in that section.

The second question presented is what constitutes "opprobrious conduct" in the context of an employee's comments on social media. To be more precise: the NLRA generally prohibits employers from terminating an employee based on that employee's union-related activity. But even an employee engaged in protected activity "can, by opprobrious conduct, lose the protection of the [NLRA.]"3 We are thus required to resolve whether an employee's Facebook post insulting his boss's mother and encouraging other employees to vote for the union ought to receive protection under Sections 8(a)(1) and 8(a)(3) of NLRA.4

We hold that Pier Sixty has not shown the existence of an "extraordinary circumstance" that requires us to waive the ordinary rule against considering arguments not presented to the Board as required by 29 U.S.C. § 160(e). We therefore do not reach the merits of the challenge to Acting General Counsel Solomon's appointment. We also affirm the NLRB's determination that Pier Sixty violated Sections 8(a)(1) and 8(a)(3) by discharging Hernan Perez since Perez's conduct was not so "opprobrious" as to lose the protection of the NLRA. Our decision rests heavily on the deference afforded to NLRB factual findings, made following a six-day bench trial informed by the specific social and cultural context in this case. We note, however, that Perez's conduct sits at the outer-bounds of protected, union-related comments for the reasons laid out below.

Accordingly, we GRANT the Board's application for enforcement and DENY Pier Sixty's cross-petition for review.

BACKGROUND

Pier Sixty operates a catering company in New York, N.Y. In early 2011, many of its service employees began seeking union representation. Following what the parties substantially agree was a tense organizing campaign that included threats from management that employees could be penalized or discharged for union activities, Pier Sixty employees voted to unionize in an October 27, 2011 election.5

Two days before that election, Hernan Perez was working as a server at a Pier Sixty venue. A supervisor, Robert McSweeney, gave Perez and two other servers various directions in what the NLRB's opinion describes as a "harsh tone."6 These directions included "Turn your head that way [towards the guests] and stop chitchatting," and "Spread out, move, move."7 McSweeney's attitude in delivering these instructions upset Perez, who viewed them as the latest instance of the management's continuing disrespect for employees. About forty-five minutes later, during an authorized break from work, Perez used his iPhone to post the following message on his Facebook page:

"Bob" referred to McSweeney. Perez knew that his Facebook "friends," including ten coworkers, would be able to see the post; the post was also publicly accessible, although Perez may not have known so at the time.9 Perez took down the post three days later, on October 28, 2011. The post had already come to the attention of the management of Pier Sixty which, following an investigation, fired Perez on November 9, 2011.10

Later that day, Perez filed a charge with the NLRB alleging that he had been terminated in retaliation for "protected concerted activities." On December 15, 2011, Evelyn Gonzalez, who had led organizing efforts at Pier Sixty, filed a second charge, alleging various unfair labor practices in violation of Section 8(a)(1) of the NLRA. On August 24, 2012, NLRB Region Two issued an amended complaint consolidating those two charges.11

On April 18, 2013, the presiding Administrative Law Judge ("ALJ") issued a decision finding, as relevant here, that Pier Sixty had violated Sections 8(a)(1) and 8(a)(3) of the NLRA by discharging Perez in retaliation for protected activity.12 Pier Sixty filed exceptions, and a three-member panel of the NLRB affirmed the ALJ's decision, with one member dissenting. The NLRB filed an application for enforcement, and Pier Sixty filed a cross-petition for review that are now before this Court.

JURISDICTION

While both parties agree that we have jurisdiction, we nonetheless consider the issue independently.13 As an initial matter, the Board had jurisdiction over the original petition under 29 U.S.C. § 160(a)-(c), which empowers the Board to prevent unfair labor practices.14 Exercising that power, the Board issued a final order in this matter on March 31, 2015.15 Since Pier Sixty is located in New York and transacts business within this Circuit, we have jurisdiction over both the Board's petition for enforcement of that order, under Section 10(e) of the NLRA,16 and Pier Sixty's cross-petition for review of that order, under Section 10(f) of the NLRA.17

DISCUSSION

A. The Validity of the Acting General Counsel's Appointment

As an initial matter, we address Pier Sixty's argument that the Court cannot enforce the NLRB decision because the complaint against Pier Sixty was not authorized by law. We do not reach the merits of this FVRA challenge because Pier Sixty has forfeited the issue by not raising it in the proceedings before the Board.

In making this argument, Pier Sixty relies entirely on SW General, Inc. v. NLRB, a recent decision of the Court of Appeals for the District of Columbia Circuit ("D.C. Circuit"), which held that the NLRB's Acting General Counsel Solomon — under whose authority the complaint against Pier Sixty issued — served in violation of the FVRA, 5 U.S.C. §§ 3345 et seq.18 The Supreme Court recently affirmed that decision and adopted the D.C. Circuit's interpretation of the FVRA. Once President Obama nominated Solomon (on January 5, 2011) to serve as General Counsel, the Supreme Court concluded, the FVRA prohibited Solomon from continuing his service as Acting General Counsel.19 Pier Sixty argues that because the complaint here was issued under the purported authority of Solomon as Acting General Counsel on August 24, 2012, it was invalid.

But unlike the petitioner in SW General, Pier Sixty never raised this argument before the Board. Pursuant to 29 U.S.C. § 160(e), "[n]o objection that has not been urged before the Board ... shall be considered by the court, unless the failure or neglect to urge such objection shall be excused because of extraordinary circumstances." Our precedents make clear, moreover, that even an apparently meritorious challenge to the authority of an NLRB agent in itself does not qualify as an "exceptional circumstance" allowing the party to raise the argument for the first time before our Court.20

While we recognize that this issue, generally construed, has divided various panels of the Courts of Appeals,21 Pier Sixty does not even cite or acknowledge any of those cases — aside, of course, from asking us to "take judicial notice of the [D.C. Circuit's opinion in] SW General"22 — let alone address any of the arguments with which those panels have grappled. Our Court has already addressed the matter, so we need not be long detained by these other decisions; we simply note that to the extent Pier Sixty's "arguments" might be construed as requesting us to reconsider our precedents, we decline to do so. Accordingly, we conclude that Pier Sixty forfeited its FVRA challenge.

B. The NLRB's Decision That Pier Sixty Violated the NLRA by Discharging Perez

We now turn to the second question presented — namely, whether the NLRB's petition for enforcement should be granted. That question itself turns on a more particular one: was Perez's Facebook post so "opprobrious" as to lose the protection that the NLRA affords union-related speech?

In answering that question, we will accept the NLRB's factual findings "if they are supported by substantial evidence in light of the record as a whole."23 Substantial evidence means "such relevant evidence as a reasonable mind might accept as adequate to support a conclusion."24 Furthermore, we will not disturb the Board's adoption of an ALJ's credibility determinations unless "the testimony is hopelessly incredible or the findings flatly contradict either the law of nature or undisputed documentary testimony."25 While we review the NLRB's legal conclusions de novo,26 "[l]egal conclusions based upon the Board's expertise should receive, pursuant to longstanding Supreme Court precedent, considerable deference."27

The NLRA generally prohibits employers from discharging an employee for concerted or union-related activity. Specifically, Section 7 of the NLRA guarantees employees the right "to engage in ... concerted activities for the purpose of collective bargaining or other mutual aid or protection."28 Determining whether an activity falls within the meaning of Section 7 is a task that "implicates [the Board's] expertise in labor relations" and is for "the Board to perform in the first instance."29

This right to engage in union-related activity is protected by Sections 8(a)(1) and 8(a)(3) of the NLRA, which prohibit an employer from discharging employees for participating in protected, union-related activity under Section 7.30 But even an employee engaged in ostensibly protected activity may act "in such an abusive manner that he loses the protection" of the NLRA.31 The parties disagree about the proper framework for identifying "abusive" behavior.

The "abusive" behavior at issue here is Perez's use of obscenities in the workplace. Traditionally, the starting point for evaluating whether an employee's "uttering of... obscenities" in the workplace qualifies for protection under the NLRA has been the four-factor test established by the NLRB in Atlantic Steel.32 That test considers: "(1) the place of the discussion; (2) the subject matter of the discussion; (3) the nature of the employee's outburst; and (4) whether the outburst was, in any way, provoked by an employer's unfair labor practice."33

But the Atlantic Steel test has come under pressure in recent years. In NLRB v. Starbucks, this Court concluded that the Atlantic Steel test gave insufficient weight to employers' interests in preventing employees' outbursts "in a public place in the presence of customers" and we suggested more balanced standards for evaluating "opprobrious" conduct in that context.34 We remanded the cause to the NLRB to develop an appropriate test for determining the NLRA's "protection for an employee who, while discussing employment issues, utters obscenities in the presence of customers."35

At about the same time, the General Counsel's Office began developing new guidance for evaluating an employee's use of social media that went in a more employee-friendly direction and that limited the ability of employers to issue rules regarding use of social media, even where employees were posting public criticisms of their employers and workplace.36 This new guidance built upon a regularly-observed distinction between activity outside the workplace and confrontations in the immediate presence of coworkers or customers.37 In light of the General Counsel's new guidance, the Board has utilized the nine-factor "totality of the circumstances" test in recent social media cases.38

In the present case, after adopting the ALJ's factual findings, the Board analyzed Perez's Facebook post using the nine-factor "totality of the circumstances" test. While we are not convinced the amorphous "totality of the circumstances" test adequately balances an employer's interests,39 Pier Sixty did not object to the ALJ's use of the test in evaluating Perez's statements before the Board. For that reason, we need not, and do not, address the validity of that test in this opinion.40

Instead, Pier Sixty argues that the Board's decision — that "Perez" comments were not so egregious as to exceed the Act's protection"41 — is not supported by "substantial evidence" in the record. It is not entirely clear whether Pier Sixty is challenging the factual findings of the Board or its legal conclusions. Regardless of whether we are reviewing the factual findings under a "substantial evidence" standard or the legal conclusions under a "considerable deference" standard, the Board's decision in this case is justified.42 Several factors inform our conclusion.

First, even though Perez's message was dominated by vulgar attacks on McSweeney and his family, the "subject matter" of the message included workplace concerns — management's allegedly disrespectful treatment of employees, and the upcoming union election. Pier Sixty had demonstrated its hostility toward employees' union activities in the period immediately prior to the representation election and proximate to Perez's post. Pier Sixty had threatened to rescind benefits and/or fire employees who voted for unionization.43 It also had enforced a "no talk" rule on groups of employees, including Perez and Gonzalez, who were prevented by McSweeney from discussing the Union. Perez's Facebook post explicitly protested mistreatment by management and exhorted employees to "Vote YES for the UNION."44 Thus, the Board could reasonably determine that Perez's outburst was not an idiosyncratic reaction to a manager's request but part of a tense debate over managerial mistreatment in the period before the representation election.

Second, Pier Sixty consistently tolerated profanity among its workers. The ALJ found that Pier Sixty had not previously disciplined employees for widespread profanity in the workplace, including the words "fuck" and "motherfucker," among other expletives and racial slurs. The Board relied on evidence that, in the context of daily obscenities, Pier Sixty only issued five written warnings to employees for such an offense in the six years prior to Perez's discharge. And there was no evidence that Pier Sixty has ever discharged an employee solely for the use of offensive language. The ALJ specifically credited employee testimony that Chef DeMaiolo and McSweeney cursed at employees on a daily basis including screaming phrases such as "What the fuck are you doing?," "Motherfucker," and "Are you guys fucking stupid?"45 We recognize that one could draw a distinction between generalized scatology (or even cursing at someone), and, on the other hand, cursing someone's mother and family.46 But one could reasonably decide, as the ALJ did in this case, that Perez's comments "were not a slur against McSweeney's family but, rather, an epithet directed to McSweeney himself."47 Under the circumstances presented here, it is striking that Perez — who had been a server at Pier Sixty for thirteen years — was fired for profanities two days before the Union election when no employee had ever before been sanctioned (much less fired) for profanity.

Third, the "location" of Perez's comments was an online forum that is a key medium of communication among coworkers and a tool for organization in the modern era. While a Facebook post may be visible to the whole world, including actual and potential customers, as Pier Sixty argues, Perez's outburst was not in the immediate presence of customers nor did it disrupt the catering event.48 Furthermore, Perez asserts that he mistakenly thought that his Facebook page was private and took the post down three days later, upon learning that it was publicly accessible. We thus conclude, according appropriate deference to the Board's factual findings and interpretation of the NLRA, that the Board did not err in ruling that Perez's Facebook post, although vulgar and inappropriate, was not so egregious as to exceed the NLRA's protection. Nor was his Facebook post equivalent to a "public outburst" in the presence of customers and thus can reasonably be distinguished from other cases of "opprobrious conduct."49

In sum, Pier Sixty has failed to meet its burden of showing that Perez's behavior was so egregious as to lose the protection of the NLRA under the Board's "totality-of-the-circumstances" test. However, we note that this case seems to us to sit at the outer-bounds of protected, union-related comments, and any test for evaluating "opprobrious conduct" must be sufficiently sensitive to employers' legitimate disciplinary interests, as we have previously cautioned.50 We have considered all of Pier Sixty's objections to enforcement and have found them to be without merit.

CONCLUSION

To summarize, we hold as follows:

For the foregoing reasons, we GRANT the Board's application for enforcement and DENY Pier Sixty's cross-petition for review.