Why would he want to spend his time and energy (in...oh, I don't know, but let's say October, 2006) to fight this?
And, if the Feds had a strong, open and shut case, they never would have accepted the deal.
Please don't underestimate the political witch hunt at the core of this "investigation".
Can you imagine raising a million for leukemia and than meeting your lawyer and going through this bs at the PD? All in a day's work, I guess.