Everybody has there bad days. He might have got caught, but if he really wanted to do damage, do you not think he could've? He got very far and into tonnes of machins before he did get caught. And the CIA has did this before (in other areas too, such as cheque fraud, where the fraudster eventually gets caught, but get of free if they work with the CIA and in collaboration with banks to prevent Cheque fraud). Perhaps they'll train him or a software security firm would be interested.
If he was to do such a thing, he wouldn't have to serve his jail sentence, brobably a very loose one anyway.