I wouldn't extend the Confederacy analogy that far. Ukrainian nationalists were in an enemy-of-my-enemy-is-my-friend situation during WW2, right up until the Gestapo arrested and imprisoned some of them. In contrast, the American Civil War had a singular motive: slavery. WW2 was much more complex, with alliances of convenience between parties that would otherwise be opposed to each other.

Arguably the biggest alliance of convenience was the Allies. The US supplied massive amounts of armaments even before officially entering the war through the "Lend Lease Act". It then continued to be an official ally to the Soviet Union. But almost immediately after Germany and Japan fell, the underlying hostility between the two powers was restored in the form of the Cold War. All that is to say, judging people simply by alliances made during WW2 is a shallow judgement.