I still haven't seen any of the trial evidence so I don't have a fully informed opinion.
My point with the statement you quoted was merely that Michael's decision about Terri was defined prior to the legal action, and it's not surprising that he'd be unwilling to change his mind after that date.
Greer's orders and the opinions of the Florida 2nd District Court of Appeals are a good window. I've been able to sort through the various contentions here on FR regarding testimony that was excluded (e.g., Terri's friend's testimony that Micahals said "How the hell would I know what she would want? We never talked about that") or found not-believeable (e.g., Terri's mom relating a conversation that she and Terri had when Terri was 18, but the court concluded Terri was 11, so mom's testimony was not believable). Those points also appear in the court records. The extraneous information (e.g., the timing of Michael's recollection, withholding of therapy, and so on) is not really in dispute, even though it isn't part of the testimonial record.
All in all, it's an easy call for me, that Greer blew the finding of fact. Terri would not want to die as long as she was comfortable; and she would likely prefer staying alive in discomfort if her life brought love and joy to her siblings and parents.
But, the law is the law, and it reached the opposite conclusion. Once a finding of fact is reached in a civil matter, the burden of proof shifts to the losing party. Not a big deal when all that hangs in the balance is money, e.g., contested will. A bigger deal when the issue is custody, e.g., who gets to keep the kids. ANd an irreversible deal when life hangs in the balance.