The Left is upset because their beloved Soviet Union didn’t get the spoils and occupied at least half of Japan, like they did Germany.
And there’s no question that Japan would have been divided, just like Korea, with the result another Civil War that would have likely gotten even more Japanese and Americans killed down the road.
I recently read a history of Japan. It included just a bit about MacArthur.
The Russian Ambassador, a general told MacArthur that the Russians were going to occupy Hokkaido. MacArthur informed him that if a single Russian soldier entered Japan, he would have the ambassador immediately shot.