I really dont understand Adultwork, if I slandered someone accusing them of this, I would think on 99% of websites the owners would be rushing to take this down worried about legal action. It makes it an easy way to black mail a girl, dont do this or that, piss me off and I will put this on your feedback, or a rival girl in the area could get her own back on another more popular girl by posting she has an STI on her feedback under an alias. I think it's absolutely disgusting.
I would see if you can get any legal advice on this, maybe tell Adultwork if they dont take it down you will talk to a solicitor.
I dont think what I am saying is extreme, I find this frightening that any one of us here could become the victim of this.