I kinda like the theory of the fact that ben had to die as a youngster and become "undead" and then surpass widmore as the leader. I just don't think that the time travel works like that, meaning i don't think that ben linus had been shot and had grown up with that experience until exactly when Sayid came back in time on the Ajira Airlines and shot a young Ben Linus shortly after. He didn't grow up with the experience of being shot. I think that after that happened, assuming young linus didn't die, Ben was given that memory as his present self. This was how it happened for a young Charles Widmore when visited by a time-traveling John Locke, he got the memory but he remembered it as if it had really happened that long ago. This was how it was for Desmond when he got the memory of Faraday, he woke up and had that memory. The fact is that ben, for example, did not grow up knowing he had been shot by a stranger only to later find out it was a man named Sayid who had crashed on Oceanic 815 on the island where he was. All of that memory and the memories that go along with growing up with that experience, right then, were given to the older ben and were a part of him. Does he know that all of a sudden he got these memories, maybe... probably. It seemed like desmond did, and it almost seemed like Widmore new that he hadn't truly had the memory of John Locke in the 50's forever. He new that John had been time-travelling and encountered him somewhat recently, John tells him that it was only 3 days ago that that happened.