I realize that this puts you in a very difficult position. That you are running a business, and that you have to ask what action could help or hurt your business here. I also know that you have much better information on your market than I do. Many guys in that market will feel betrayed if all of a member's postings can be censored due to providers' complaints about him. It sets a disturbing precedent, and I'm uncomfortable with that, too.
However, ask yourself this: what motivates a man to abuse a provider and then post a false review about it? Most sessions are unreviewed, you know. It would be far easier for him to write no review, wouldn't it? He must be getting some extra pleasure from doing this, now. If he's writing false reviews, it must be a way for him to insult her further, and to tell her how powerless she is. Perhaps also he feels powerful manipulating "the system" to humiliate.
TER has no control over whether this guy is going to get better, stay the same, or get worse. But that's not the point. After the forewarning you've had, if he does get worse, you don't want to be found tied to his gonads at the crime scene. Suppose, worse case scenario, he ends up with a body count, providers or non-providers. The family is distraught and angry. They want to sue somebody. Lawsuits tend to follow the money. It won't take a great lawyer to find TER, and find that you had enough information to know that he was manipulating you to heighten his own pleasure.
And, if it goes to trial, you're probably going have at least six women on the jury. They will all hear how some guy used TER Reviews to insult and humiliate, and they will get and understand the insults right away. No matter who they are, housewives, providers, nuns or grandmothers, they will vote against you as a block. Good luck with the rest of the jury.
Besides the major reason I've given you here, I have a minor, personal reason for wanting you to have a procedure regarding this. I don't feel as motivated to read reviews when the staff has been told, by several providers, that a guy is writing false reviews. There are a lot of porn sites on the internet.
/Zin