Krugman is right when he said this (from your link):
Iceland did not engage in fiscal stimulus; it didn’t have to, given the kick from a huge depreciation of the currency. It did, however, have a quite effective program of mortgage debt relief that is a role model for countries like the United States.
Currency depreciation is a form of stimulus. So is mortgage debt relief. As usual, Keynes was right and those in favor of austerity were wrong.