I don't know if its just me that missed something or what but why would he want to make himself vulnerable? As an edo he can never die, and has unlimited chakra. As a mortal, he will eventually exhaust himself. Now he has 4 top notch edo kages to deal with as well so its not like he'd be able to become the juubi jin a split second after reviving himself. He'd still have to fight them off which I highly doubt he could do as a mortal.