If a court determined that he breached, there could be damages for losses to the company based on his breach, i.e. it could go beyond him just giving back what they gave him. This is really the kind of thing where you need a lawyer's guidance based on very specific facts.
My point is that they haven't given him anything, thus there is no contract. The company can try and sue him for breach of contract but the issue is whether or not a contract actually exists. Of course a lawyer should always be involved to make sure that everything is ok legally.
