Because when it comes to Times writers like Harwood making outside media appearance, the Times' newsroom standard is quite clear [emphasis added]:

In deciding whether to make a radio, television or Internet appearances, a staff member should consider its probable tone and content to make sure they are consistent with Times standards. Staff members should avoid strident, theatrical forums that emphasize punditry and reckless opinion-mongering. Instead we should offer thoughtful and retrospective analysis. Generally a staff member should not say anything on radio, television or the Internet that could not appear under his or her byline in The Times.

Yet on Monday, Harwood, appearing on MSNBC, derided liberal critics of the proposed health care legislation as “insane,” claimed they should have “their heads examined,” and mocked their commentary posted online as being naive and “really idiotic.”

Question: Were those comments that Harwood would likely make under his New York Times byline? No. Were Harwood's attacks “strident”? Yes? Did he engage in “reckless opinion-mongering” Yes.

Like I said, Harwood might want to re-read the newspaper's Ethical Journalism handbook before his next TV appearance.

UPDATED: It's interesting that Harwood became so angry at liberal bloggers over a policy difference. It's telling because I don't recall Harwood taking to the airwaves this year and denouncing right-wing bloggers as they peddled incessant Obama-is-a-racist-socialist-communist-Nazi attacks. That kind of commentary apparently did not anger Harwood. But when libs online took issue with legislative policy, Harwood could hardly see straight.

UPDATED: FYI, The Times' guidelines cover both staff writers and “nonstaff contributors.”