I don't accept that any members of the SS were merely harmless nationalists. If they weren't die-hard Nazis they would have enlisted in different units.
And actually, I understand that in Europe the only two choices at one time were Communism and Nazism. To fight one was almost automatically to align with the other.
Thank G-d that America's traditional veneration of the TaNa"KH has prevented such a situation in this country.
I don't think that was the prevention. It was that communism didn't gain a lot in the US due to the flexibility of the workforce and the acceptance of true capitalism rather than cronyism
however, that all may change thanks to Obama...