Krugman is a little upset with some of his commenter's insults.
Get your insults right. There is, I believe, a fair bit of evidence against the hypothesis that I’m stupid. What you mean to say is that I’m evil.
I think what his commenters are trying to say is that he often makes stupid arguments because he is evil (which in internet discourse means they have different ideologies) or because he is too obsessed with his clever models that he underestimates the real world consequences of some of his arguments.
The basic point is that the recession of 2001 wasn't a typical postwar slump, brought on when an inflation-fighting Fed raises interest rates and easily ended by a snapback in housing and consumer spending when the Fed brings rates back down again. This was a prewar-style recession, a morning after brought on by irrational exuberance. To fight this recession the Fed needs more than a snapback; it needs soaring household spending to offset moribund business investment. And to do that, as Paul McCulley of Pimco put it, Alan Greenspan needs to create a housing bubble to replace the Nasdaq bubble.