When the quest to eradicate Nazis turns the eradicator into something at least asbad as the Nazis themselves…
There were so many people, even children, drafted and forced to serve the Nazis, either in the military or in other capacities. Many of which returned as broken, disabled and traumatized shadows of themselves. Genociding them for being abused by the Nazis would seriously not be better than what the Nazis did.
(Disclaimer: I am totally not defending Nazis or Neonazis here. But history is complicated and messy and there where millions of people who just did what they were told out of fear of their own lives and the lives of their loved ones. Also, history is largely written by the winners. Had the Nazis won the war, then we would now talk about the concentration camps for Japanese people in the US, and about the gulags. I wish that we could get rid of Nazis, but genocide cannot be fought by genocide and you cannot fight fascists by becoming one.)