A person or entity can not be held responsible for the actions of another. This will be defeated rather easily, otherwise car manufacturers would be liable for what people driving there cars do with them. They (feds) can make a case for regulation under the commerce clause since many escourts conduct itra & interstate commercial activities, but that would just require a login to identify the seller and purchaser for the purpose of tax collection for an illegal activity.
The real money issue is, who wants to spend the money to fight this law, because it would need to travel up food chain before it's struck down.