I'm gonna go out on a limb and say he's not worried about what will happen at the school he wants to withdraw from, but rather what will happen at the school he wants to attend. Because that whole "withdrawing you automatically" thing could be a bitch...
But anyways OP, schools ain't gonna do anything to you yet. If you're actually calling to withdraw today, I would also take the time to call up the school you're sticking with, and let them know of your decision.