Any professor who is not ashamed of what he or she is saying in class should welcome being recorded.
And any student taking a class with a professor who objects to being recorded should know that this objection is almost always equivalent to the professor saying: “I want you to hear what I say in class because I’m quite confident that you can’t differentiate between instruction and indoctrination. But if what I say goes public, people who do know the difference will expose me as a propagandist.”