Just supposition, but the person you point to in your example may have been so far 'gone' physically that the organs did shut down and they passed before the effects of starvation could become evident.
It is my understanding that in Terri's case, aside from brain injury, the rest of her body was functioning normally. Thus the effects of starvation could become much more apparent and causal in her demise.
Just an opinion.
That is probably close to true. The overall progression was extremely swift - five weeks from diagnosis to death - but as I recall that the 'final phase' was about 7 or 8 days after the decision to wrap things up (the timing is somewhat blurry in my recollection, because of how jarring it all was and also because I had to leave for a couple of days and go back). He was on very heavy morphine, fwiw, and it was probably the morphine that actually killed him in the end I suspect (though not officially, of course).