I'm going to say to you as a mod, and I hope you understand that your need for clarification has caused me to skirt into banned topics.
Don't worry about just making the factual statement: The National Socialist German Workers' Party was antisemitic.
I have no problem with that kind of statement; I don't think anyone at Paradox would deny the factual nature of that statement or be angry of you made that statement.
The rules are focused genocide, war crimes, POW camps, and that sort of thing. We don't have time to discuss why, but never feel that Paradox thinks there is something wrong with claiming that Nazis were antisemitic. It's discussions focused on how that antisemitism (along with a bunch of other things) was enforced in policy during the war that becomes a thorny issue.
The Nazis couldn't run a nuclear program because much of the necessary science was invented by Jewish people. "What if the Nazis hadn't been anti semitic?" is a stupid question since then they would cease to be Nazis. They would be some other conservative party.
I hate to say this, but let's be fair to the tenets of National Socialism as practiced in Germany during the 30s. If you examine the 25 Points program announced by Hitler in 1920, it is very clear that NSDAP was not just "conservative + antisemitism" or "conservative + racism." There were several policies/demands for change that clashed with conservatism as practiced in Germany (and many other places).
For example, the reason the word socialist is involved is because of the desire for the party to be more, well, socialist. This included demands for the nationalization of industries, abolition of certain kinds of debt, abolition of unearned incomes, the demand that every capable German be given a higher education, demands to outlaw child labor, demands to increase national health through programs, land reform (and abolition of land speculation), confiscation of war profits, and so on. Even Goebbels in his diaries mentions more than once that the party needs to become more socialist (pre-1935). They practically stole 1/3 of the socialist's platform and melded it with racial supremacy and totalitarianism. You can't really call it conservative.
Now, could Nazis have been Nazis without being antisemitic? No, it was a fundamental plank of their platform. In that time and place, you can't really separate the two. In a hypothetical world with a fictional country and fictional culture, there is no need for antisemitism as such in fascist ideology; however, fascism in every form I've ever seen it, requires a scapegoat for the ills of the state. If not antisemitism, then something else would have to fill that role.
With that said, I think that while you could make a case that the science itself being viewed as Jewish slowed down production, I consider the loss of scientists who left to be much worse. Nazi Germany practically shot itself in the damn foot when guys like Einstein decided it was time to leave or not come back when abroad. Germany's lack of access to certain materials useful in nuclear research and production was also a factor, but without the brains, no project of that kind could have been successful.