His worshippers keep saying he's not stupid, and because it's Friday, I'm giving them the benefit of the doubt. That leaves only bribery as the answer. I don't know the specifics. Might involve cash, might involve some sort of harmless job at Lockheed.
If you can come up with a 3rd reason why Bush-2 would reverse a decision made by his father, who was definitely NOT stupid, I'd like to hear your idea.