For all the issues with Rowling, her allusions to Nazis in Harry Potter was fairly good. People in those stories said they were forced to do evil using a charm, and it made it almost impossible to identify "real" Nazis and the ones who "didn't know better" or "couldn't stop it." The same is true for Nazis in real life. The people will say they didn't know or just kept their heads down to avoid trouble, but how do you know if they're telling the truth?

The answer is, you can't. You can be generous and just let them all go free (and bring Nazism back later) or be aggressive and root out the problem.

I have no idea if this is on purpose, but it's made pretty clear how to solve the issue in the first place, and I'm pretty sure she doesn't agree with it. She has obvious "former Nazis" doing Nazi things in the open, but then no one does anything to stop them. How much simpler would the story have been if they had just killed the Nazis?