I ran across this the other night. Pointing you to it because it seems to offer a complementary counterpoint to your benefit of the doubt point of view.
That piece doesn't address Sullivan's change circa 2006-08. IIRC, he Began to oppose the Iraq war, and the republican party, where he had been a strong supporter previously.
I never shared Sullivan's views. I could be misremembering how much he shifted in that period, since I didn't follow him closely. But the article doesn't address those years, only earlier times. (which sound pretty bad, if the characterization is accurate)
Edit: here is a piece that comments on Ames and Sullivan. It's how I remember his later writing. No moral hero, but a man clearly aware that he made an enormous error on iraq.
http://pando.com/2015/01/28/andrew-sullivan-is-not-the-futur...