How smart of him. He really needs more arms.
If you watched, he said that he hasn't trained arms in a month, Hany told him not to do so because well, like you said. So they theory is that he can train arms a a month at a time and not lose the size, shape or fullness. Basically it seems like they are trying to bring up his other bodyparts, like chest.
Interesting, what he said, which was almost word for word what Shawn Ray had said The Final Countdown-right after he was posing (after he trained chest): "Not satisfied, there's still work to be done"