I'd be willing to bet, that along with that contract, he has a No Compete. If they are going to pay him through 2011, he better honor that no compete agreement.
If he goes to work for someone else, CBS will void the contract and he won't get paid. If he breaks the contract, he'll likely wind up in court. Although if he really wanted, he can beat the No Compete agreement, as those don't fly in TX. Just depends on if he wants to deal with the hassle, and spend the money to do so.