This was definitely the right thing to do. Giving him an even larger megaphone was a mistake, but it happens. The good news is that they've corrected the problem and are moving on. Greg Sargant at the Plum Line received an email from the Huffington Post on the situation:
The Huffington Post is committed to fostering a lively and often provocative debate about the issues of the day and encourages a wide range of voices from all perspectives to participate. Andrew Brietbart’s false ad hominem attack on Van Jones in The Daily Caller violates the tenets of debate and civil discourse we have strived for since the day we launched. As a result, we will no longer feature his posts on the front page.
He is welcome to continue publishing his work on HuffPost provided it adheres to our editorial guidelines, as the two posts he published on HuffPost did -- guidelines that include a strict prohibition on ad hominem attacks. Our decision today recognizes that placing posts on the front page is an editorial call that elevates some posts over others, and is an indication of how seriously we take these judgment calls.
