I like his first footnote especially: "While Paul Krugman is a Keynesian, not all Keynesians agree with Paul Krugman. As such, any Keynesian reader who takes offense at the criticism aimed at Krugman and equivocated with general Keynesian theory should recognize that this characterization is meant for the sake of simplicity."
I have to wonder - was he thinking of me? Anticipating criticism, clarifying, and qualifying is always very good practice. In other words: always make sure you cover your ass.