Krugman, and his ilk, are incapable of being honest. If they were, they would have to admit that over and over again the policies they advocate result in disaster.
You don't seem to be aware of the fact that Krugman has always said that the 2009 stimulus act was far too small. Another fun tidbit: the actual price tag of the act as passed is less than $800 billion, not a trillion. I believe a one trillion version was considered in congress before this smaller compromise passed, perhaps that's what you were thinking of.
Bu let's not get bogged down by technicalities. Something passed Congress. You didn't like it because you think the idea itself is bad. Krugman didn't like it because he wanted it to have been far larger. And now today you're using the results of something Krugman didn't like to say "See? Krugman is wrong!"
Economics is not a science. We do not have models of the real economy that are adequate for accurate quantitative prediction of behavior. Krugman is a careful thinker and observes that the qualitative behavior of the economy in this instance behaves as would be predicted under the Keynesian rubric.
