Put simpler: Paul is your 49th vote to repeal and your 51st vote to keep it.To be perfectly frank, Paul was probably just angling to get an "I voted for a clean repeal" vote on his record to back up his Ayn Rand schtick. That was never going to pass, and he knew that, but he still wanted it on record. Now that he has that, the GOP will need another bribe to get his vote back.
He is a free rider exploiting the current situation and will refuse to be the deciding vote.