I just went through a month with a 90 year old friend whose life ended almost exactly like the story in that story. He had one lucid 30 mins when I was there and his family was there (he had been a general physician for almost 50 years). In his brief period when he had the energy to try and communicate whilst almost totally paralysed, it was clear he was telling the attending doctor that he wanted them to stop all medication and let him die. His own family could not face that fact, and said they'd ask him again the following day (unfortunately the cowardly doctor backed them up on this). He was never again lucid or strong enough to insist that treatment be stopped. He lived for another 10 days, struggling to breathe, almost totally paralysed, unable to control his bowels.
This was a man who when I last went on holiday with him at the age of 85, he insisted on carrying his own suitcase and refused a wheelchair, even though he had trouble walking and had blood pressure and angina problems.
I don't blame his family not being able to make that decision (it's so hard to let go of someone one loves). But his last weeks were undoubtedly torture, and they know they refused to follow his wishes. It was just terribly sad and an awful dilemma.
I was really glad of something else I read on HN about 6 months ago, where a doctor had a brain tumouur (or something like that) and instead of treatment, he lived out the remainder of his life doing the things he loved. I think that idea was what meant I could come to terms with the need to respect my friend's last wishes. I just could not convince his family.