A couple of us went in to talk to the boss about a plan just submitted that morning and he actually had to reach into the trash can for it. At least he had the grace to say that he must have knocked it off the corner of his desk.
Surprise, surprise, the plan wasn't accepted.
I think the PHB handled the situation very well! He probably had no idea of the technical merits of Dilbert's proposal, but was able to avoid losing face by saying so, and Dilbert should feel happy believing his idea was vindicated in principle. The "political reasons I can't share" is a great example of plausible deniability.