Nothing legally unpleasant happened, therefore no legal liability. Containment's enough.

That's the porno party line again. Resourceful.

I doubt the whole clean porno shit.
Veterans - old whores and whore fuckers - never having contracted any STDs or STIs? No way. It doesn't matter, except to the producers covering their asses, if that's what happened. Symptomatic and asymptomatic diseases and infections have been passed on sets, during outcalls and at home, I assume.
Since no one keeps track of it all and no one's to be trusted completely in this regard due to hooking being illegal almost everywhere, you can say that nothing went down, just not prove it. The opposite's difficult to prove, too. Happy business.