Read other letters about this article
Like Michael Harold on page 2 of this comment stream, I made a post to Alter's comment section that was not printed by Huffington Post. At the time I made the post, there was just a single comment visible under the article. When I checked the article an hour later, there were several more comments, and I noticed something unusual. The lone comment I had seen before was no longer the first comment, it was preceded by a comment referring to Glenn's criticism of Broder here on this blog. Clearly, this post had been held back for a time while the site editor considered whether to publish it or not.
I think it's also quite clear that Huffington Post exerts editorial control over their comment sections.