First off, I don't really believe that he can't, maybe at the end of a long workout he couldn't, or if he didn't like whoever he was working out for, maybe he wasn't willing to push himself.

But what you don't realize is that comparing him to you is waayy wrong. His arms are what over 7 feet long? Do you realize how far down his elbows are when the weight is on his chest? Not to mention the fact that when he's pushing it up, he probably ends up benching twice the distance that you bench? Go take some physics classes, in this case work=force x distance, his benches could easily "work" as hard as many lifting 300lbs.

You don't see very many long armed bench pressers, and there is a reason why.