The article goes on about this pressure sore, but I don't think that's why he wants to die.
It quotes him saying that he doesn't want to be a burden, and as he's a fairly new quadriplegic (less than two years) who's had multiple health issues during that time (including other pressure sores), I think his mind was already made up long before this sore.
He basically can't accept his disability.
Obviously, the hospital needs to get their shit together, but this situation goes way deeper than a sore (no pun intended).