If they believe kicking you out instead of your harasser is less risky they won't hesitate twice to do so. I can confirm that from personal experience.
If you can afford it get legal advice first ... and then go to HR.
Also I believe most employment discrimination employees will work on a contingency basis, so you should consider reaching out to them regardless of your financial situation.
I understand the constant refrain from HN of never trust hr, but I think reporting to hr could form a better foundation for a lawsuit. Feel free to contact an attorney first. That is what I would do.
As the initial point of contact for a sexual harassment complaint, beginning to construct a paper trail that explains the superior's behavior and puts blame for the incident on the employee?
I'm not saying this as pro- or anti-HR, just that as the document-keeper of record they have a lot of latitude to influence the narrative if they choose to. Remember: performance reviews tend to go through them at some point as well.
I think the point should be not to trust HR with the only copies of any documents or evidence. Again, I would argue that if HR does the steps you suggest, they are exposing themselves to much more risk than if they did pretty much anything else. Not to say they wouldn't do it, but that it would be a foolish thing to do.
In the UK, for instance, terminating someone for reporting sexual harassment is a very good way of losing a lot of money at a subsequent Employee Tribunal and getting your company fined. There's a lot of great precedent for siding with the reporter, even if other flimsy reasons are given for their termination.
However, the point made is a correct one. An HR person has a duty not to you but to the company, so never assume they have your best interests at heart.
If your case is as clear-cut as the one in this article you might indeed not need a lawyer but if there's any wiggle room; if it's discrimination and not harassment and the accused is sufficiently important to the company and HR judges that you might not have the energy to file a lawsuit etc. etc. etc. then it's still very easy to end up getting kicked out of the company.
And if you can't, join a union (or form one if they don't exist), they can help pay for legal advice and/or have their own lawyers.