> If you say "I don't know about that", or "I'm not sure if that really happened", it's a short walk from tolerating fascists.

I strongly disagree. There is an enormous shift from "I question whether Jews were killed" to "Let's go kill Jews".

(To avoid misunderstandings and red herrings: Yes, the Holocaust happened, and was very much as horrific as claimed. The evidence is clear, consistent, overwhelming, and almost impossible to deny. And there are almost certainly recruiters who use "just asking questions" to try to recruit people. Nevertheless, "shut up and stop asking" isn't the answer. Instead, the answer is to show evidence, in overwhelming amounts. This may not silence the recruiter, but the recruiter isn't the target of your evidence. The recruitee is.)