I've done a little bodybuilding in the past and I would wager to say that it could actually hurt your climbing. Larger muscles need more oxygen and fuel, and tend to burn out faster than muscles that are just conditioned for the task at hand. Bodybuilders, in a way, train their muscles to cramp up. And believe me, that sucks up in the tree.
I remember the first time I tried bodythrusting up a rope. I was in top shape for me. I thought I was gonna show this tree climber dude how wimpy he was. Of course I was all arms with no thrust. I ascended about 6 feet and I was done. Felt like a fool. But I learned that you don't build climbing muscles without climbing.
I've aways felt the thin, lanky climbers were the best, but I'm sure you could argue the point either way.