It is often quite messy over the choice of #2 and often a financial based one. Sure, if he outright stinks it will be easy to cut him. But there is a good chance that it won't be a clear cut choice especially if he can rack up good looks/stats vs 2nd and 3rd team scrubs. We all know the instant stars born in pre-season who can't tie their shoes when it counts.
On top of that, one of the jobs of the #2 guy is getting the #1 guy ready every week. Is CK good at that and/or would he accept that role? Sure, it is easy to back up a Tom Brady/Aaron Rodgers type but what if he ends up backing up at Jacksonville /Tennessee /Bronco/Redskins'Chargers where the second the starter struggles, there will be instant questioning/demand by some that CK be given a shot.
I'm betting if he gets a chance and gets cut, there will still be those that will say that he got screwed/didn't get a fair chance because of his social stances. Any team that cuts him will end up having to bend over backwards to justify a decision that most people wouldn't even question. I'd hate to be the guy who makes the team in front of him because folks will have the microscope on him.