If this is an accurate summary of the Bishops' position (we all know paraphrases can mislead) then they are way out of line with correct teaching.
Even if, with every effort to help her, Terri were to remain in precisely the same condition for the next 50 years, it would be totally contrary to the Church's teaching to deprive her of food and water. THOU SHALT NOT KILL INNOCENT PEOPLE, PERIOD.
The LORD, in His mysterious providence, permits the Church to suffer under "shepherds" such as these. How long, O LORD?
Not a very hard concept is it?
Yet even here a lot of people have trouble with it.
Life is a gift. Deliberate murder of the innocent is wrong.
Why is there even an argument here?