He had to break the symbiosis of the suit, so he killed himself.
He couldn't even speak anymore because his body was so dependent of the suit, that the suit had to talk for him.
His body was deteriorating so much because of his dependance. It's the whole reason Lockhart was apparently against Hargreave and the Nanosuit program, his relative died because of the suit itself. He felt that the person in the suit was just a technicality, and that even if the person was dead - the suit would still function. Ironically Alcatraz is exactly that.
The symbiosis was that the suit would only work on him while he was alive. He took off the suit, put it on Alcatraz and then killed himself.
I'd need some type of reference on his body deteriorating b/c of the dependence. I distinctly remember him saying he was infected and if you look at this face you can see the exact same infection marks that all the other bodies had.
Edited by FuNkDrSpOt - 4/18/11 at 3:14pm