John couldn't say body yet. It was still Sherlock and still him. He still personalized the corpse and even then he could practically hear Sherlock telling him that was pointless and stupid. That he shouldn't make a connection to a body. It was Sherlock's way of telling him he cared. He didn't want John to hurt more than necessary, but John was already hurting. He was broken hearted and it was as plain as day on his face.
If a car was coming that meant he didn't have to lift Sherlock just yet, so he rested him back down as gingerly as he could and watched him a while longer. If he squinted a little it almost looked like he was just sleeping there. Like he'd gotten tired after dealing with Moriarty and his insanity and just couldn't make it home.
"Who is coming?" Any other situation he might have tried to make conversation, but he was too tired and too defeated to try anymore. He should have been happy that Moriarty was finally dead by his gun but he wasn't sure he'd ever feel true happiness again at that point. "I should prepare him." He still couldn't say body. He doubted that he ever would.