One of the reasons I kept Ben alive in my first playthrough was a sincere hope that he would redeem himself. I still don't think he has redeemed himself in my view, but I haven't thought about it the way you put it, Mornai, since Ben's little tirade did snap Kenny out of his depression and that can be seen as redemption. But like pretty much all things Ben, it was not intended since Ben was pretty much just whining about how terrible his life was and how people should thus lay off his inadequacies.
The one thing I do like about keeping Ben alive was that he does manages to retrieve Carley's gun, which is the last memento we have of her. Still, letting Ben fly was much more satisfying to me.