It certainly could explain it- but it does not explain his persistence in the face of doubts and her family's protestations, it doesn't explain his mockery of his marriage vows, it doesn't explain his barring her family from her many times- even in her final hour. It doesn't explain much at all other than the delay in expressing her supposed wishes.
Really, only Michael Schiavo knows why he did what he did, and so far he's not been particularly forthcoming. As is his right, of course - he doesn't owe me an explanation. Nevertheless, there are other possibilities that even I can see.