He refuses to see that each person is responsible for his or her own actions, and that if "the left-liberals in the blogosphere are merely aping the odious, disdainful—and politically successful—tone that right-wing radio talk-show hosts like Rush Limbaugh pioneered" then they do it of their own free will and choice. There is no cause whatsoever for incivility, but the hubris that Klein has to blame the Left's craziness on the Right...
It is a circular argument. Klein, an obvious apologist for the rabid blogs of the Left, has now absolved them of their blame by saying "THEY STARTED IT!"