IMHO, one of the biggest points that needs to be hammered home is that despite the existence of affidavits claiming that Terri used to take food by mouth (after her 'collapse'), Michael forbids such and such prohibition will remain in effect if gastrostomic feeding is discontinued.
If the parents were allowed to make bona fide efforts to feed Terri by mouth (and have her tested for sedatives or other drugs), with the consequence that if they succeeded she'd live and if they failed she'd die, I wouldn see that as vaguely acceptable (probably because I have faith that if God wants Terri to live, she'll be able to take food by mouth). But any person, no matter how healthy, will die if they are prevented from receiving any food or water.
Many people don't realize that the primary reason Terri needs "life support" is that Michael won't let her be fed any other way. I think if they realized that, they'd find his actions entirely repulsive.