The legal posture and conclusion is the opposite. That he was looking out for her best interests. Given her condition, and the court-determined patient's wish to be dead, her best interests were to obtain a natural death by starvation. It just happens that Michael's testimony and sense of "best interests" and the court's finding of "best interests" are congruent in this case, they needn't always be.
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.