I wonder if this man's wife is suffering from dementia or Alzheimers? His children clearly remember what their father wants, living will or no living will. I can't possibly see why someone who has been with his/her spouse for all these years would deliberately go against a spouse's spoken wishes.
Christopher Reeves was on a ventilator, and did quite well expressing his views.
This is a classic example of the slippery slope. People will be killed against their will; it is inevitable.