Because I don't buy that an otherwise reasonable and moderate guy is casually an holocaust denier.

I am specifically not arguing that anybody - including the government - should have the right to harm that person, but it's such a massive red flag that I believe I would be justified in severing all ties with that person.

I guess that even denying the holocaust, like everything else, comes in different degrees, but parent was talking about organized groups that actively attempt to spread that belief. That's too far for me to ever forgive.