You know more about the depths of that story than I do... I can only guess that some kind of "strategic thinking" went on there, balancing right vs. wrong morality with the practical need to have superior technology, essentially turning him into a "brain drain" scenario where the USA took advantage of the technology from Germany (rockets go further with higher precision), in order to use it against Russia (both in rockets meant for warfare plus also as demonstrated in a show-off capacity for the space race). And that is even assuming that he was a "real" Nazi supporter, and not just trying to blend in as a Jew (which would be bad enough, to be a "collaborator", but you get what I am saying: easier to make an exception for, especially if there was some evidence of him protesting in underground ways, as opposed to a full-on die-hard actual Nazi).

Something similar happened recently when Biden met one of the royalty responsible for the murder of Jamal Khashoggi, and decided to call him out for that murder, but when the response was "what was that? I couldn't really hear you there..." just dropped the issue entirely rather than pursued it. It was not even a slap on the wrist, and was less even than a phrase stated loudly enough to be heard (a whispered thought then?) regarding the torture, interrogation, murder and actual dismemberment of that journalist... but in return, the Saudis helped lower gas prices. And lest you think this was all about money, that in turn helped blunt the whole "thanks Biden" (sarcasm for high gas prices, as if Trump had literally nothing to do with that) that Republicans were trying to use at the time to get more seats in Congress and set up for the next Presidential race, which in turn ties back to Supreme Court seats and all sorts of things.

I am fond of quoting that literal hero Jon Stewart who once said "liberal media aims to be correct, while conservative media aims to be effective". Maybe somewhere we need to find a balance, in maintaining our morality while also not taking it to the grave with us - or perhaps the latter is what needs to be done? But if so, it seems better to do that intentionally so worth thinking through and wrestling with the truth to determine what we can "compromise" on, and what we absolutely, simply, can NOT without losing who & what we are.

And believe it or not, yes this is all absolutely, entirely, 100% relevant to the OP: Star Trek is infamous for wrestling with precisely these kinds of plots - even TNG and Voyager that were more often episodic lets-go-forth-adventuring-today styles occasionally had them (remember that time Picard was dying from his bad heart due to his poor judgement in his a youth, and Q offered him an alternate life where he would not be a captain anymore, but he could do science and really enjoy it, thus making him choose b/t a longer life that he would enjoy vs. a shorter one lived to the fullest, basically a It's a Wonderful Life parody? and ofc "THERE ARE FOUR LIGHTS!!"); but DS9 really just immersed itself and flat lived in this space.

TLDR: you are going to REALLY enjoy watching DS9, even if you need to do it alone:-). (again, make sure to give yourself adequate time to think them through, not just watch them all back-to-back, or you will miss so much!)