Well, judging by the photographs of his body being paraded triumphantly along the street while the Libyans snapped cell phone photos of it, I’d say the “no other injuries” part is a lie.
Maybe the other injuries didn’t kill him, technically, but he clearly has scrapes and bleeding all over him.
I suspect that what happened is that the Libyans dragged him out, hauled him around and possibly sodomized him (probably with a stick or some object) or at any rate abused his body if he was already dead, and then as they were jubilantly parading him along the street, some armed party arrived with a car and got his body away from them and brought him to the hospital.
Even if he had been alive when they dragged him through that opening in the wall, he was clearly dead in the later photographs (where some of the Libyans can be seen hopping up and down and grabbing their crotches in a gesture of contempt). And since he was dead, he was no longer of any use to them, so when somebody on our side appeared, they dumped his body and it was taken to the hospital.
In my opinion, that would account for the initial confusion over how he was brought to the hospital and the victory-lap photos that we have seen.
Everyone who has translated what the group was saying when they found Stevens says they were happy that he was alive. Several reports say they took him to the hospital. A doctor at the hospital reports he tried to revive him and examined him. His body was picked up at the hospital by Americans to fly him home. But you think a crazed crowd of unarmed Libyans tortured and raped him and then took him to a hospital?