There has to be more to it. You have to figure they were willing to give him a ton of slack with the baby situation and all. He's also a willing defender and didn't demand shots, just minutes. Plus, Pop tends to turn to his vets in the playoffs when the youngsters look shaky. It's likey his playing time would have increased.
Note I'm not say he should have receive more playing time or that he has anything left or that he would have made an impact. Just saying that to cut him this late with those variables, it had to be something more egregious than complaining about playing time or a general disagreement. Something had to leave Pop feeling like he had no choice.
Or maybe he's just that cold and figured T-Mac would be better. With Diaw going down there was no one left to leave off the roster. Jax was just odd man out.