While it's good news that another corrupt Bushie has been pushed out, if you hadn't noticed, there's rather a crisis right now that would fal directly under his department, and the fact that he has just resigned makes things all the more difficult. Hilzoy draws the obvious conclusion.
Take-home lesson: don't appoint dreadful people in the first place. Then they won't have to resign at the worst possible moment.
I think this lesson collides with the Bush principles of governance.