Keynes was an unapologetic financial elitist and had no interest in a quest for income equality or a planned economy. He simply sought a mechanism to get stuck markets unstuck. No one has proposed an alternative to his idea of a stimulus. The enduring nuisance is that someone has to guess about exactly how and when to aim a stimulus kick; this is just another way of saying you can't have science without scientists.
I ... don't know if I would agree, from having read Economic Possibilities for our Grandchildren + various secondary sources on Keynes, but maybe Lanier's just trying to make him more palatable for the conservatives in his audience?
this passage is situated in a larger musing on local maximums and the complicated, risky ways we can get out of them and on to higher equilibrium points (which is relevant)