"Believable" is in the eye of the beholder - it's a judgement call, limited by the extent and fallibility of human judgement, unless and until we perfect those law-dispensing machines.
One other thing -- aren't you the least bit curious as to Michael Schiavo waited until *after* winning the malpractice suits against the doctors to tell a judge about Terri's wish to die? He constantly says that he is merely fulfilling her wishes, yet he waited a good eight years before actually attempting to act on her alleged wish.
There is an alternate explanation, of course - he honestly wished for and hoped for her recovery at first, and he did apparently take steps in the early years to promote her recovery. Then as time passed and it became clear that she was not going to recover, he began considering what she might have wanted in such an event. Obviously, I don't read minds, and hence cannot say what was really going through his head at any given moment, but some process like that that would seem to explain the sequence of events fairly plausibly.
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.
Where in the world does it cost $300,000 for nursing school? Did Michael include the two new Mercedes as tuition? The mind boggles.
He already decided by 1993 that he didn't want Terri to come back, as evienced by his destroying her cats and her wedding rings. Funny he didn't remember her wishes for years after that.
The problem with that is that his and his attorney's spin has been that she's essentially been brain-dead for 15 years, not 8. Why not try to pull the feeding tube 15 years ago? After all, since Schiavo claims that's what Terri would have wanted, why the wait?
As for your "reading minds" comment, isn't that essentially what the judge in this case did? Read Terri's mind via her what her husband alleged she commented, and assume that an alleged remark about ventilators meant that she would prefer to be starved to death? And as disability activists have pointed out repeatedly, even those who claim they "wouldn't want to live that way" when it comes to being disabled often change their minds if they actually do become disabled.