You know the old saying. Dog bites man is not news. Man bites dog is news. In this case, Kos bashing Kerry is not news (although it may be something worth responding to). However, Kos saying something favorable about Kerry (beyond the 2004 Presidential campaign) is news.
Today Kos was listing things Democrats have done in which Republicans convinced the mainstream media would lead to the end of the Democratic Party. He even gave Kerry credit for one:
When Kerry filibustered Alito, that was supposed to be the end of Democratic chances in the midterms. Republicans celebrated. Democrats ran for the hills (most notably Joe Lieberman)