if an adventurous (and well-regarded) professor seriously proposed teaching such a course as an experiment, I am not sure it would be rejected out of hand at all universities
Probably no. Some universities would only fire him after the course. Assuming he would really bring some offensive material, instead of something harmless, such as... uh, something.
Actually, this is an interesting exercise:
Imagine that a university orders you to teach "discussing offensive topics", inspired by this article. But you also know that if someone gets really offended for some content of your lessons, they will fire you (despite any previous promises and guarantees). But if you refuse to teach such course, or teach something else instead, they will fire you for disobedience. Your only goal is to minimize the chance of being fired. Which topics would you discuss?
In other words, which topics can be best described as "offensive" while actually being almost safe (in a university environment).
fire
Geez, this experiment should only be attempted by tenured professors.
From Julian Sanchez, a brilliant idea unlikely to be implemented: