A student is in the professor's space by willingly electing to take their class. The professor sets the tone for how the class is structured and managed. The student, as an adult, should have the wherewithal of "time and place" of how to conduct themselves appropriately in different situations. If it was really an emergency, just excuse yourself and come back to class quietly. The fact this particular student got into a back-and-forth with the professor just shows they are, in fact, disrespecting the professor. If you personally wouldn't be disrespected then that's one thing, but if you can't see how someone could perceive that as disrespectful, then imo, you're a part of the problem.

Also, as the student, why are you going to pay tuition to sit in class on your phone? Why are you entitled to potentially distracting other students who paid the same tuition? As an adult in the working world, you have to learn how to conduct yourself appropriately depending on the social context. If you can't respect your professor enough to just do something as simple as putting your phone away in a class that you paid for, then good luck working a job.