Granted, wasn't Hitler a vegetarian and a dog lover? If only you could get rid of the overwhelming crazy some people have! Had someone travelled into the past and showed him Rob Liefeld's art, Hitler might've immigrated to the US and been the original overrated crappy comic book artist...
This is actually a translation error - though it's one of my favorites!
Japanese uses a lot of English words, but often they end up with different, though related, meanings. In Japanese, フェミニスト (feminisuto) means something more equivalent to a chivalrous gentleman.
So while they're actually trying to get across that Eggman is a well-mannered gentleman in between all the evil, I like to think that when he isn't trying to conquer the world he's super focused on women's issues.
(And for what it's worth, I always kind of liked the Sonic Adventure-era depiction of Eggman: his well-intentioned extremism actually made sense for the character when you consider that his grandfather, a brilliant, altruistic scientist that he idolized, was betrayed and driven insane by corrupt authorities. Having seen that, an ambitious young genius might well decide that, fuck it, the only way to change the world for the better is by force. My favorite games are still the ones where he's an uncomplicated asshole mad scientist, but I do think that fresh take on the character was cool.)