In the Telltale video of the Episode 4 choices, it had three outcomes for the Bell Tower Situation. One was pulling him up, another being dropping him, and the last letting Crawford take care of him (Not shooting walker). Even though I didn't drop Ben, I learned that if you run out of time, the choice "Drop him" is automatically chosen. What I think should've happened if you ran out of time is Lee just stares in disbelief at Ben, who begins purposely slip away from Lee's grasp. Lee shouts Ben's name as Ben drops down and breaks his legs.
I just think it fits not choosing anything better than just dropping him.