You conflate Terri's situation with others which are not similar.
Chew/swallow is something learned, and in her case, it could well have been re-learned through therapy.
Further, you postulate that Terri's body was "shutting down," which is manifestly untrue.
However, the Pope's body was, e.g.--so regardless of the feeding tube, he died.
The differences are extremely important.
You believe that she could have *relearned* chewing and swallowing through therapy.
Since the part of the brain which predicates that ability was no longer in existence, this potentiality was not a true possibility.
Her body had shut down over ten years ago, but the feeding tube bypassed that shutting down process.
I did not conflate the Pope's situation with Terri Shiavo's. You did.