I don't think changing professors is as easy as changing hairdressers. Let's be honest - both parties had a moral argument. What the professor asked for was a courtesy, and courtesies are by definition not mandatory.

The student was obviously a jerk, but still within her rights. It was simply a failed negotiation. And it could have depended on many factors we don't know. Since wearing a mask was an elective act, many other factors could have played a role. Maybe the student was just an entitled brat. Maybe the professor was just not very good. Maybe he had refused in the past to accomodate students in other ways. We don't know. But what we know is not enough to make definite pronouncements either way.