Moral gatekeeping, use word or ethical arguments to shut down or delegitimise statements they disagree, particularly when those statements challenge their worldview. Moral gatekeeping, using moral language to control what can be said, displaying moral superiority to shut down debate.
Using moral doctrine to make certain ideas unspeakable, you couldn’t argue for independence without seeming morally corrupt. They’re not really refuting your statement, they’re making it morally dangerous to express it which prevents debate from even happening. The real problem is once something becomes morally wrong rather than debatable, discussion stops. That’s a powerful control. more effective than direct censorship.