There was a similar but more extreme example in Weston-Super-Mare a couple of years ago. Profile written by the master, who takes the money and then lets you use his slave, who is tied up and blindfolded, she never actually sees the punter.
I wondered then about the legality of it, though he did display a photograph of a "slave contract" in which she gave consent - it could still be classed as "controlling prostitution for gain". The profile disappeared after a few months, then eventually reappeared again, but written by the slave (or from her perspective anyhow - "my master" rather than "my slave"). Then it disappeared again.
BDSM is an area where the law should tread lightly. The illusion of control by another, and a lack of consent, is often a part of it - but it's actually still consensual, as the slave has volunteered.