The 2002 column was about the Fed's difficulties in fighting a recession caused by the NASDAQ bubble bursting, and that since the NASDAQ bubble was unsustainable, that the only way to return to the same level would be another bubble, and that perhaps Alan Greenspan was trying to do just that.
"Greenspan needs to..." was what Greenspan "needed to do" to make his rosy predictions come true, not what he needed to do for the good of the nation of the health of the economy.
The comment by Pimco's Paul MCulley to which Krugman was referring was:
"There is room for the Fed to create a bubble in housing prices, if necessary, to sustain American hedonism. And I think the Fed has the will to do so, even though political correctness would demand that Mr. Greenspan deny any such thing."