If an employee you are responsible for and are in close contact reports they are sexually assaulted by another employee you are also responsible for then yes, you absolutely call the police. Stop trying to make it sound like Bowman just overheard the story at a bar about like a former roommate or some shit. It was his employees that he oversaw and his responsibility. As for victim's privacy, you can have that and still involve the police, hence why we have other unnamed victims in this case, because they have chosen so.
Why is it difficult to understand here that if a boss hears one of his employees was sexually assaulted by another employee, the ONLY correct action is to get the police involved. He was told by higher ups that they were gonna take care of it? Fine, wait a bit, but when it is clear those people are not going to do anything, when it is clear the sexual predator is just going to get off scott free and be able to offend again, you have a moral obligation to act and Bowman did not. He sat on his hands and let it happen.
A woman goes to her boss and says her co-worker raped and attempted to murder her, but she is afraid of what will happen if she reports it.
Boss: Oh well we will just let it slide then, I mean I only heard it 2nd hand anyways and since you are afraid I won't bother encouraging you to be brave and offer supports. We'll just ignore it ever happened instead.