The guy in question has "Lockdown Syndrome" where his mind is 100% able to still do everything else he could, but he is paralyzed from the neck down. No form of treatment or cure.
On the flippedy side, I used to have a mate who had muscular dystrophy . He had no control over any of his body parts (including his lungs - he was on a respirator 24/7) and was in a leccy wheelchair, needed a round-the-clock carer etc...and he was no word of a lie, the happiest and funniest motherfucker I ever knew, no way would he have chosen to go...his body was just unusable but his mind was still sharp as a sharp sharpie.
Horses for courses.