It would be good to know if there were any "mission" left for Terri to accomplish. That is where I think prayer and priesthood blessings would go a long way towards making the right decision here. But these people don't have that, so they are relying on their understanding. And I do not fault them for the conclusions they have come to because I know for ME I would hope they would come to that conclusion.
It may be wrong to end Terri's life, I'm not 100% sure either way. But knowing how I would feel if I were in that situation, I do not condemn them (her dh, other who support him) for their decision. That's all I'm saying.