The FBI needs to accept that shutting down these sites is not a sustainable option. Instead, it should cultivate the sites that are in US jurisdiction, and allow them to operate, so that the FBI can use them to monitor illicit activity.
Prositution is a victimless crime. Human trafficking is not. Unfortunately, without legalizing and regulating prostitution worldwide, it's impossible to disambiguate between an autonomous sex worker and a human trafficking victim. But sites like these can really help with that disambiguation.
The FBI should be working toward this disambiguation. It should be filtering out the sex workers from the human trafficking victims, because the latter are the only actual victims in this business.
The FBI needs to realize that sites like these are an asset to the fight against human trafficking, because they facilitate monitoring and analyzing the market. Shutting down these sites will not even make a dent in the demand for prositution. It will simply drive that demand elsewhere, to underground sites or ones outside of FBI jurisdiction.
This is a loss for human trafficking victims. By pushing this business further underground, the FBI loses some monitoring and detection ability, traffickers are likely angry, and victims lose the benefit of client accountability on sites like Myredbook. This shutdown will not affect the supply of, or demand for, human trafficking victims. It will only worsen their situation and further hide it from authorities.
But hey, the FBI gets some nice PR pieces about their latest big bust! Yeah! Go team! Such a formidable cyber security force!
[1] I invented the word "Hydratic," but it should totally become a thing.