Right. But that aspect of his character isn't really dependent on the holocaust. It just needs a sufficiently equal event to shape his views in a similar fashion. Since it is all fiction it doesn't matter if it is lived history or not. Because his version isn't lived history no matter how much it relies on the events. Your Luke Cage comparison is just flat out dumb. Equating a different genocide-level event to being left handed is a set up for failure before you even finished typing that sentence.
It's not like Marvel hasn't done changes before including gender, race, and stuff. But changing the race of a minority representation is a little bit different of a beast then an origin. And Marvel has already done a line of comics with him having an origin that is a descendant of holocaust survivors rather then a direct participant. And its not like Wanda's story hasn't changed several times including at one time being a child of Magneto.