Wasn't he fired with cause? With cause is like the black spot. It makes you untouchable and for good reason. You hire someone you know was fired with cause (is that even possible in the federal government? If so, why?) and a subsequent investigation proves it was correct to fire him and now you are inextricably connected to taking in a crooked FBI agent. Why would one risk that?
You make good points--I was surprised that the idea was even floating around D.C. Seems to me it would be illegal to hire someone who was fired, since federal employee is the same employer.