Query on unscheduled parent meeting

An elementary chapter leader asks:

I want to know if a teacher has the right to leave an unscheduled meeting with a parent and an administrator when the parent is rude, offensive and very hostile and the administrator does nothing to mediate/intervene on the educator's behalf. Personally, I think anyone who feels that the atmosphere in a meeting is unsafe, physically or emotionally, ought to be able to remove themselves.

Any ideas?