He might be lending the girls to the club on condition that they're protected from dipshits like Warren and other sorts of abuse from the clients. Just another way for them to make some money when they aren't doing the porn flicks.
Donovan mentions that plenty of girls wash out after 1-2 movies and seemingly no one cares to chase them with guns and whatnot to keep them in business. There's so much churn in the industry no one is going to obsess over one random whore. Other than her son who discovers her movies few years down the road, apparently.