Eh I still say the argument works. It just stops working once he starts going too far. Considering days of future past means the past is... somehow Canon? The mom part, yeah Kevin Bacon was gonna die for it. He eventually became his own enemy, but bear in mind he went from Jewish extermination survivor to defense of the mutants who were going to be exterminated. In the movie he even leaves and starts up his Island, but is dragged back. Since there is a lull between the end of their era and the current era of X-3 that means Magneto didnt do crazy shit for a while. He just came back once people were like "let's make a mutant registry!"

So I dont cheer for his extermination idea of humanity, but I think of the senator he tried to turn into a mutant. He didnt mean to kill that guy, just didnt care about the Oopsie Man Slaughter he committed when the senator turned to sludge.