Re: A bioethicist weighs in: Was Cheney too old for a transplant?
If he was competent, his is the only directive which matters. Friends and family, including those with a Power of Attorney for Health Care don't matter.
The surgeons can refuse to do it if in their opinion there isn't a chance of survival.
If he passed within 24 hours of the decision he must have been in poor condition.
There may have been other factors, too. The colon surgery may have had a 10% chance of survival, and he may still have been left with metastatic cancers all over the place.
And you are absolutely correct. He was the "decider" while he was competent.