It is ignorant to say a non interventionist foreign policy is the same as doing what dictators tell us to do. I have said US involvement in WWII was avoidable, and it totally was. Your problem is not with me, it is with the Constitution, which is why I think someone should propose an amendment stating that our military should be used throughout the world without a declaration of war. That way, at least we'd have the Constitutional basis for doing what we have been doing for so many years.
I’m not sure WWII could have been completely avoided. It’s an interesting proposition because if we hadn’t given aid to the British or Chinese, it would have been interesting to see whether or not the Japanese would have seen us as a threat. I believe eventually Imperial Japan would have attacked us in some way, perhaps one of our military outposts in the Pacific or even the Philippines, which they did right around the same time as Pearl Harbor. But the administration certainly wasn’t trying to stay neutral.
Ultimately (assuming we never got involved) I think the Russians would have overwhelmed the Germans and the Chinese population would have been too much for the Japanese to handle. But it’s all hypothetical.