You must be single or a teenager, otherwise you would understand. It's pretty simple. Would Bruce like to finish out his contract? Of course, but not if it means uprooting his wife and kids who have been in the SA community for 7+ seasons. He has 2 stores in SA he runs and he has a degree (sports communications/broadcasting, I think). That would be selfish, especially if he doesn't really NEED the money.
So best case scenario for Bruce: he gets bought out (free $$$) and re-signs with SA.
Worst case: he gets traded, tells his new team he's retiring so you may as well waive me, and he starts his life AFTER basketball a year earlier than he planned. He's already been filling in on talk radio as a host and has done a great job.
Either way, his family comes first and they stay in San Antonio, rather than move and live somewhere for a year, only to move BACK to SA next summer.