Sullivan wasn’t a leftist! He was a right-winger - the original publisher of the Bell Curve in TNR - who went extremely right over Iraq and called for people to be imprisoned for opposing the war, and then had a repentance arc and went nominally liberal for a while before returning to form.
BeijingPalmer
The link with Yglesias is a good point. From memory he was one of many self-proclaimed leftists/liberals who achieved mainstream success via his support for US foreign policy, the main way back then of showing the establishment you weren't a threat
