Well, I don't like speaking for other, but if it help the dev save some time for other thing, then I will try. So about your question, in a way, it is avoidable. The choise about showing the picture to her mother lead to that scene.
So if you don't show her the picture, take the good path, she won't be in a gangbang, and will be "safe".
And if you show her, you take the dark path, as the dev said to someone I don't want to name, the content about some choise are clearly show, and that one involve sharing. (With man, sadly apparantly not girl or other living being.)
And so, if you wanted the dark path, I am not the dev, but I don't think he will make it avoidable.