So I just discovered that I have been working next to the waste of oxygen that raped my best friend several years ago. I work in a manufacturing environment and I know that you can’t fire someone just for being a sex offender unless it directly interferes with work duties (in the US). But despite it being a primarily male workforce he does work with several women who have no idea what he is. He literally followed a woman home, broke into her house, and raped her. Him working here puts every female employee at risk. How is that not an unsafe working environment? How is it at even legal to employ him anywhere where he will have contact with women?
The short and unsatisfactory answer to your question is that this isn’t a hostile work environment. A hostile work environment is narrowly defined. You telling everyone about his rape of your friend is closer to the definition than him being a rapist.
An unsafe work environment applies only to physical hazard, so the same goes there. You’d have to demonstrate and prove that he is causing you current harm. Basically, unless he sexually harasses you or attempts to rape you, and you can prove it, there is no leg for you to stand on.
The law was built by men. It’s built on what has happened, not what could happen. It doesn’t protect victims, only inconsistently avenge. The bulk of protections in place are for accused/ perpetrators.