In this context, it was completely irrelevant.
Because unlike your naive presumption, this killing of Terri has nothing to do with mercy or releasing her, and everything to do with paving the way for further abuse of conscious, alive people with brain damage.
Dehumanization is the trend. Where the trend is leading seems to be toward organ "donation".
And if you spent the time I do reading the medical journals, especially the letters, you would see this as clearly as I do.