I presume the issue here is that the DA did not believe they could prove beyond reasonable doubt that this was assault and not a model regretting she did a porn

I presume the issue here is that the DA did not believe they could prove beyond reasonable doubt that this was assault and not a model regretting she did a porn shoot. It vaguely sounds like they had an OF that did a bunch of these shoots, and presumably the DA didn't manage to get any other girls on record saying they were assaulted (how hard they tried etc is unclear).