Chait is a big admirer of (and apologist for) Krugman; he has defended Krugman's pathological obsession with Bush (and Krugman's lies about his Enron kickbacks) on numerous occasions.
Chait is also obsessed with labeling Bush as a "liar" on just about every issue other than Iraq (Chait is a hawk on that issue). This would probably be a more impressive line of argument if a) Bush was actually lying and b) Chait had a track record of being bothered by politicians who lie. Chait showed no such indignation toward Bush's predecessor and his lies, so his outrage is rather selective.
If you read Chait's writing, you sense that he still hasn't figured out what he is: A bright guy making neo-liberal arguments about taxes or a snide Carville-esque child trying to echo Paul Krugman with soundbites and ridiculous accusations. The piece you posted is strong evidence for the latter theory.
Finally, Chait has been among the most strident outside of the far left in attacking Social Security privatization. He's intelligent enough to know that stocks provide a much better long-term rate of return than the Social Security funds, so one wonders what his real agenda is. The most logical conclusion is that he fears people having their own retirement accounts independent of government largesse.
Chait could be a lot more useful as a writer if he'd be more intellectually honest and less cute and glib in his writing.