No idea who Mullen is, but these whores should take a lesson from "journeymen" in other industries, who take a hit on their pay when the demand is lower. I guess in this case, these whores can always go escort for higher rates, but at higher risk.
Why would the whores be offended by a lowball offer? The offer would be meaningless unless they were interested in accepting it. They can sit at home "tweeting" and earning nothing only so long, only to come to find that the demand may not be there when they finally decide to lower their rates.
This is actually an interesting economics problem; they outlined a similar one in the first Freakonomics book, describing the behaviour in the housing market of buyers, sellers, and the real estate agents. Despite how the agents may instruct their clients, the same agents often behave entirely differently when it comes to selling their own homes than they do when representing clients. Since Derek Hay used to consider himself male talent, it would be instructive to inspect his own booking history in a market climate similar to today's. Unfortunately, it is not published anywhere to give the other side of the story.