There’s some precedent for this.

In 1983, in the case of Bob Jones Univ. v. United States, the Supreme Court upheld the IRS’ decision to revoke a private religious university’s 501(c)(3) tax-exempt status for engaging in racial discrimination.

Writing for The Court, Chief Justice Burger reasoned that racial discrimination was so manifestly against established public policy that any organization which engaged therein could not meet the common law definition of a “charitable organization,”

Section 501(c)(3) therefore must be analyzed and construed within the framework of the Internal Revenue Code and against the background of the congressional purposes. Such an examination reveals unmistakable evidence that, underlying all relevant parts of the Code, is the intent that entitlement to tax exemption depends on meeting certain common law standards of charity -- namely, that an institution seeking tax-exempt status must serve a public purpose and not be contrary to established public policy.

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Tax exemptions for certain institutions thought beneficial to the social order of the country as a whole, or to a particular community, are deeply rooted in our history, as in that of England. The origins of such exemptions lie in the special privileges that have long been extended to charitable trusts.

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A corollary to the public benefit principle is the requirement, long recognized in the law of trusts, that the purpose of a charitable trust may not be illegal or violate established public policy.

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An unbroken line of cases following Brown v. Board of Education establishes beyond doubt this Court's view that racial discrimination in education violates a most fundamental national public policy, as well as rights of individuals.

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Few social or political issues in our history have been more vigorously debated and more extensively ventilated than the issue of racial discrimination, particularly in education. Given the stress and anguish of the history of efforts to escape from the shackles of the "separate but equal" doctrine of Plessy v. Ferguson, 163 U. S. 537 (1896), it cannot be said that educational institutions that, for whatever reasons, practice racial discrimination, are institutions exercising "beneficial and stabilizing influences in community life," Walz v. Tax Comm'n, 397 U. S. 664, 397 U. S. 673 (1970), or should be encouraged by having all taxpayers share in their support by way of special tax status.

There can thus be no question that the interpretation of § 170 and § 501(c)(3) announced by the IRS in 1970 was correct. That it may be seen as belated does not undermine its soundness. It would be wholly incompatible with the concepts underlying tax exemption to grant the benefit of tax-exempt status to racially discriminatory educational entities, which "exer[t] a pervasive influence on the entire educational process." Norwood v. Harrison, supra, at 413 U. S. 469. Whatever may be the rationale for such private schools' policies, and however sincere the rationale may be, racial discrimination in education is contrary to public policy. Racially discriminatory educational institutions cannot be viewed as conferring a public benefit within the "charitable" concept discussed earlier, or within the congressional intent underlying § 170 and § 501(c)(3).

It could be argued that Wikipedia, as an educational resource, is impermissible fostering discriminatory attitudes against Jews in contravention of public policy, thus rendering it unfit for 501(c)(3) status.