He became eligible for a no-fault divorce 3 years after Terri was incapacitated. Why doesn't he file for one?
I suspect you, my wise friend, already know the answer, but I'll throw it out here for public consumption--three reasons in ascending order of importance/likelihood. BTW, in the first few days, he was probably not thinking coolly, and item 3 was the only one in place at that point.
1. Abusive men are first and foremost possessive. Terri, though damaged, was still "his."
2. He may have seen dollar signs. Once it became clear that the doctors weren't detecting her true cause of injury, he probably realized he could pin the brain damage on them and collect a settlement.
3. By far the most important: He stays next-of-kin, he's in charge. If he stays in charge, the medical decisions can be steered so that she never gets to a point where she can say, "Heart attack? No, the last thing I remember is Michael hitting me with a 2 X 4."
And that is why he will say "I love my wife and want to stay married to her," when he has been saying "I'm done with her" loud and clear in real life and the courts for years now.