Oh Dr SEGA Monkey, you have no idea about the incidents!
To iron out bugs? Maybe some acts aren't completed yet? I dunno, the guy never said everything was completed. Doesn't mean the physics will change though. The physics aren't necessarily buggy, they're just....really weird for a Sonic game and not right for "Sonic 4".
They are buggy, Sonic jumps and launches himself really far in the air, he gets stuck and doesn't go back down a curve, he also doesn't fall down a horizontal wall when he is
walking. If that isn't a bug, I don't know what is.
The guy also said the game was getting it's set rating and being evaluated by Microsoft so no changes can be made, that sounds like SEGA aren't going to be doing anything for the next five months.