I believe he is not saying the site owners are traffickers but that some OF channels could be trafficker run.
But the proper incentives would need to be in place. She'd need to be allowed to stay in country if she is a foreign victim of trafficking, for example. We would want to prevent this from becoming some type of guild where incumbents can keep out new competition. And the police would need to be supportive in this process (i.e. promptly inform OF of models' eligibility, and otherwise participate in the process in good faith). It's hard to see that happening in, e.g., the United States.