that's gotta be staged. He has a right to not want his students using cell phones, but, especially in a college setting, there has to be some kind of respect between students and profs. Students pay his salary, and if they choose to not pay attention in his class, their loss, and their decision. Professor can decide to kick someone out of their class, but they can't destroy personal property. It's not like 2nd grade, where the teach can jack your video game till the end of the year.
If it were my phone he'd just destroyed, it would be either his car, tires, or his ass, as soon as I had my grade. That is, unless he agreed to reimburse me for the phone.