I have never posted that I think a fight is fixed however did Ustinov's right hand even land? To me it sure looks like Harris rolled didn't get hit and went down acting like he was knocked out cold.
Watching on YouTube it looks fairly clear that Harris got hit with the right hand. It was hardly a clean shot but it did land in a particularly sensitive spot, though he seemed to recover awfully quickly once the fight was stopped and I can understand suspicions.