You're right ... but this unChristian idea seems to be at the heart of the public reaction to this case.
The question people are debating is, "Are we going to allow the disabled to live?" There's an almost overwhelming rejection of the value of a disabled person's life. Even many FReepers' comments are on the order of, "I'm making sure my Living Will makes it perfectly clear that I want to be DEAD, rather than disabled." And much of the discussion of Terri Schiavo seems to suggest that, if her condition never improves, then at some point in the future it would be acceptable to kill her.
It's a fearful prospect, being severely disabled, and something new for me to address spiritually ... I believe I'm prepared to die and be with the LORD, but am I prepared to accept that His will may allow me to be disabled, helpless, a "burden," perhaps for many years?
In a way, it's a parallel to our spiritual condition: we are all "disabled" before God, unable by our own efforts to overcome our sin and be united with Him. If we accept this, why can't we accept that we may at some time be physically disabled, and reliant on the "grace" of others for the continuance of our physical lives?