You are misrepresenting the Church's doctrine that you link to. The Catholic Church does not teach that it is ever permissible to starve someone to death because they have low quality of life.
You are confusing Terri's case with that of someone who is terminally ill, and for whom consuming food can only heighten excruciating pain. The two cases are very different.
That's not true. You didn't read the link I posted from the Council of Bishops. Read it carefully. I found at least two instances in which Terri qualified.
They also mentioned, not that this pertains to Terri, but if the burden of a feeding tube became too expensive it was permissable.
I was quite shocked at just how many instances there were that made it permissable to let a patient die from starvation.
This is in the Catholic Conference of Bishops official policy as linked earlier:
Since the best current medical opinion holds that persons in the persistent vegetative state (PVS) are incapable now or in the future of conscious, free human acts, these moralists conclude that, when careful diagnosis verifies this condition, it is not obligatory to prolong life by such interventions as a respirator, antibiotics, or medically assisted hydration and nutrition.