"[I] tried to explain: There was an uprising against Germany, but the Russians were across the river, and on the German side there were also soldiers from Hungary or Ukraine," he said. "For Americans, it was completely incomprehensible, too complicated, because they grew up in a different historical context, where everything was arranged: America is always good, the rest are the bad guys. And there are no complications
I think that's the point, in the books Geralt starts off as a cynical centrist completely opposed to taking a side in any conflict. Over the course of the books as his character develops, he learns to care about more than just what immediately affects him.
He starts off that way in the show too but he's less of a smug redditor about it.