By virtue of being nazis they have forfeited the protections of the social contract. I don't give a fuck about the dehumanization or human rights angle, when a thing exists for the sole purpose of destroying society (like nazism and any supremacism) you remove it by any means necessary from society. You do not allow it to continue because if you do, it will destroy you. Fascism is an existential threat and killing fascists is always self defense.

They gave those up within their ideology

I'll kill a charging polar bear too even though I love animals