One of the mistakes Germans (+ occupying forces) and the Austrians made after WW II was pardoning / "washing clean" Nazis after the war. Eg. the Austrian far right party FPÖ was founded by an SS member, and I'd be surprised if the AfD didn't have Nazis in its family tree as well.
People who support fascism can't be rehabilitated, except for a tiny minority.
And as we all know, the best way to prevent anyone from attacking you is to make sure you're as defenseless as possible