This, of course, assumes that he would have decided for some different reason to hold off from shooting a guy who wouldn't be able to yell or sing, unbagged him, and then allowed that mutilated version of himself to crawl off.
He was also kind of retarded, so I won't entirely dismiss that possibility.
There was that speech about not killing them but doing something worse to them, but either scenario as soon as it started his future self would have vanished from where he was. The ending just highlights a lot of the problems by making old Joe disappear like that.
They should have all just vanished from the field because most of the film never happened.
They should have all just vanished from the field because most of the film never happened.