Since he had sole control over much of the evidence dealing with her actual condition, I would say his credibility (or lack thereof) affects the reliability of both types of findings.
What evidence exists that would contradict the notion that Terri was clearly not PVS, but Michael et al. were trying to hide that fact? Note that people not employed by Michael or Greer almost unanimously perceived that Terri was trying to communicate. Michael et al. downplayed those observations, of course, proclaiming all such people biased, but when all of the 'unfiltered' evidence says 'not PVS', the integrity of the guy doing the 'filtering' would seem to say a lot about the reliability of any 'PVS' finding, would it not?
He attempted to carefully manage the evidence after that fact, although he didn't do a great job of it. The videos were created, and we've all seen them.
But the determination of whether Terri was in a PVS at the time of the trial rested entirely on the credibility of the physicians who testified, not Michael's word or his opinion.
His unwillingness to revisit the issue of Terri's condition after the trial and especially before the tube was removed for the last time probably indicates that he was afraid that a new look might reverse the earlier ruling. I think it does. But his opinion of her condition is irrelevant from a judicial standpoint.
I'm splitting hairs here, I know, especially since I think there should have been new tests from a moral standpoint, if nothing else.