I find that doubtful, considering the "personality" of the Japanese at the time and how long the USSR spent on Germany's Eastern Front before the Western Front was even opened. Beyond that, we knew that the USSR wasn't going to "threaten" to invade, it just would. A Soviet occupied Japan(begin moralizing) was seen as a worse outcome than an American one.
Considering what happened to Eastern Europe at the hands of Stalin and the USSR, I think if we're looking at the "big picture" in hindsight, a Soviet-occupied Japan would have been a much worse outcome, both for international politics throughout the next few decades and for the Japanese people.