Givin the time and preperation Kabuto would have beaten Obito. Why did he chose not to? Was he really afraid?
What kabuto was 100 times stronger than j-man he had madara an DSMUnless he knew for certain the one he was fighting was the Actual Tobi and not just a Renn Puppet, it would be foolish to start that battle. We all know how that went for J-Man.