Of course Carey won't start, he's the 4th guard for crying out loud. Don't give this lunatic fringe the legitimacy of thinking this is an actual consideration.
As for making the PG a time share, the backup pg position is being won by Battle. The Battle/Buddy combo beats out any JC combo. Giving more time to JC would have stunted the chemistry growth between Battle and Buddy.
JC (as 4th guard) had a rare late season (last 3rd) opportunity to earn more PT. He failed miserably (again).
So the question shouldn't be does JC start, it should be does JC warrant any more time this season? When does JB pull the plug?