The chances of gunplay are much less than the chances of a physical assault not involving guns.
Did you misunderstand the phrase "worst case?"
Either she trusts the photographer or not. Period. And if she doesn't trust him then she shouldn't be talking to him and shouldn't be going to a shoot with him. Escorted or solo. Clothed or nude. Whatever. If the "photographer" really is the type of person who would attack a woman then neither an escort nor some pieces of fabric concealing her naughty bits are going to stop him. They might make him take other measures, like giving roofies to both her and the escort, or it might mean he brings along 2 "assistants" to handle the escort, or it might make him wait till the next day when the escort is gone and she's on her way to work in the morning, or any number of other things.