Why are wingnuts afraid to debate?

This is funny:

Right-wing blogger Michelle Malkin has been a leader in the infamous smearing of a 12-year-old boy and his family in the political debate over President Bush's veto of the State Children's Health Insurance Program.

In a valiant response, liberal blogger Ezra Klein (right), a bright lad of only 23, has challenged the much older Malkin (she'll be 37 next week) to a debate on the issue of health care, but Malkin has chickened out, which has prompted other progressive bloggers to mock and taunt her.

UPDATE: There's more taunting of Milken here, here and here.