The guys from Scientology's PR department requested moderated comments with (I suppose) overtly negative comments removed. As they were paying for the content to be run, they were free to request any terms and conditions that they desired. The Atlantic was free to accept or refuse the terms and conditions and in this instance chose to accept them.

For what it's worth I found it interesting to hear comments from people outing themselves as enthusiastic Scientologists. First time I've come across that on the web.