Only because the first options of reaching out to department members and administration went completely ignored. I certainly wouldn't file a formal complaint a

Only because the first options of reaching out to department members and administration went completely ignored. I certainly wouldn't file a formal complaint as my first action in this case (as described), but at a minimum the people who work there have experience dealing with situations like this, and could offer advice to the professor, or perhaps have a discussion with the administration about how to prevent this situation from escalating into a Title IX issue.