Yes.
What if Greer decided that 1) Terri was conscious and 2) she was unable to communicate?
Michael and the other Schiavos could still have said that Terri would not want to live "this way."
Michael would still have had the final word and could still have decided to starve and dehydrate her.
Terri screaming when she learned the tube was coming out in March of 2005, the 18th or 17th, didn't mean a thing. She wasn't afraid. It was just a reflex action. (yeah right). Terri was horrified because they'd tried to kill her twice before!