"Believe survivors" and "Believe everything people say, regardless of context, details and backstory" are not the same thing.
This happens again and again, and people fall for it. If the faulty logic and psychology of this isn't enough, this whole sort of thing being sockpuppeted by known abusers who run fascist training/staging grounds should be. This includes taking advantage of conflicts, because that seeds their discord all the better.
This shouldn't be hard, but *shrugs*