Give anyone an excuse and they’ll hate the Pope. But such was predicted by Our Lord Himself for those who follow Him.
If this guy wasn’t the Pope, and had the same history, and he stayed in the Hitler Youth for over a year, would you be suspecting him?
Granted, they shouldn’t be planning physical attacks on him; but I can understand the sentiment of having a little resentment towards him if you saw your relatives sent to the ovens - regardless if there is repentance or not.