There you go again.
You conveniently left off only if they must be fed as part of life support.
You conveniently forget that a pacemaker is more 'life support' than a feeding tube is.
There are plenty of severely handicapped that cannot feed themselves.
Maybe in your world, we can set up a "life, not worth living" advisory board, who can decide who gets to stew in their own unflushed poisons.
"only if they must be fed as part of life support."
Lots of people require I-V's, sometimes for days, after they have surgery. I guess if they don't regain consciousness fast enough to suit their "guardian", he can have the I-V stopped to ease their suffering, is that right? I'm just asking; I'm no medical expert like some people here.