Generally speaking whenever a celeb, be it a footballer, actor etc. goes on a reality TV documentary, it means one thing: they are off their game and their career is on the wane.
I'm going to stick my neck out and suggest it's exactly the same for hookers.
Also, in a business that's based on discretion, it's not terribly professional to be doing this whilst still in the job. Fair enough to do a documentary after retirement if you keep anonymity.