When we can't protect and care for the innocent and helpless, we become what we hate.
Can you give guarantees that using their daughter as a guinea pig can restore her to even 5% of the life she had before? Does Terri Schiavo have any cognition? Does she know what's happening around her? Does she have a life beyond lying in a hospital bed for years on end? How many times a day does she involuntarily defecate and urinate? Have you ever taken care of comatose and vegetative state patients? Have you ever wiped the feces from their rectums and buttocks (if they haven't smeared it all over their bodies and put their feces-covered hands in their mouths, as some are wont to do)? How many hours a week do you work or volunteer at a hospice or nursing home?
As for me, if I were in this state, I have already made sure that my family knows that I would not want to exist in this condition by exercising a living will. Why? Because, after caring for patients like these, I may have the capacity to breathe, process nutrition, defecate and urinate, only the body is present. My ability to think, function, have any cognition is long gone. My soul is waiting for the body to join it.