Really, as much as I may not agree with the man's politics (cf. his treachery on Obamacare), I don't want to speak poorly of a dying man who is obviously very ill... but seriously...
He still hasn't resigned? How valuable is that seat to him that he won't let it go until they pry it from his cold, dead hands?
I hope and wish that his passing is peaceful, and for comfort toward his next of kin, for the sole reason that they're human beings. Still, he's dead wrong (pardon the pun) for doing this. He deprived his constituents of representation for no other reason than his own ego, knowing full well that this was going to happen. If he can decide to discontinue treatment and die, he can resign with dignity.