I suspect that, in any other context from the particular one he found, where he was taken seriously, Hitler would have been an eccentric bore - "There comes old Adolf again" they'd say in the pub when he started ranting on about some bee in his bonnet.

But, unless those ideas about quantum splitting multiple universes are true, and they found some way of observing them, there's no possible way in which anyone can ever find out what the truth is about these things. "What's the evidence?" asked Joe F - and it seems to me that, by definition, there can be no evidence either way.