There's certain men who preach feminism and its tropes but don't truly believe nor practice what they preach, but hold others to their standards.

What do you say about a lobbyist who works against their own kind?

With cigarettes, you'd say they're "in the pocket of big tobacco."

With medicine, you'd say they're "in the pocket of big pharma."

So then, what about feminism? A man who preaches social justice, white knighting, and other destructive things.

Well, those men are in the pocket of big vagina.

Made me laugh but I think it fits.