I think the main risk would be a deterioration in the government's finances since the government is expecting to get paid back and is factoring in those payments to the financial outlook. That could in turn lead to an increase in the government's borrowing costs, which could affect lots of other things negatively.
And the fact that he even delivered, to me, is a testament to his superhuman programming abilities. Especially considering that this was all in assembly langauge. And the Atari 2600 is notoriously difficult to develop for, even as assembly language development goes...