I see much of the argument here is about "facilitating prostitution," that such facilitation would trump free speech protections, both constitutionally and in other laws. But the opposite is true, as highlighted by the EFF, third parties, who are not involved in the illegal activity have a right to discuss that activity and do not take responsibility for the actions or postings of others. With respect to the Internet, there is a federal law, section 230 of the Communications Decency Act of 1996, which states that Web service providers cannot be "treated as the publisher or speaker of any information provided by another information content provider".
> third parties, who are not involved in the illegal activity have a right to discuss that activity
What you're missing here is that they don't have a right to make money off of it. RedBook weren't just facilitating the discussion of illegal activity, they were making money out of the advertisements on the site. They were directly involved in the illegal activity.
Actually, advertisements were free. They made money on enhanced reviews of providers and clients. In other words, one could, for a fee, dig deeper into reading comments between and about users of myredbook.
The owners of myredbook were still a third party in these comments and did remove postings that could encourage child prostitution, robberies, or other serious violent crimes.
