It's been a while since I've seen the film but didn't he get shot in the heart by not one, but TWO javelin sized arrows tipped with neuro-toxin? I mean how do you come back from that? We know they have viable cloning technology, but what would be the point in this case? Cyborg maybe? Most likely, but you'd think for that to be even feasible they'd have to have rushed him to a medical facility just to get him stabilized. Also, he went down on a battlefield in the middle of a jungle. You'd think he would have been just left to rot.