As Charlie is blind, deaf, and cannot move, it is likely that he is unable to show whether (or not) he is experiencing any pain. And apparently the doctors at GOSH cannot state for certain whether he is.
If he was crying and screaming 24/7 the parents may take a different view of whether he should be allowed to pass with dignity.
As long as he suffers in silence, I can understand them clutching at any straws that may present themselves.

A case worthy of Solomon.