I don't think that this one situation demonstrates racism by the police force. Or even be "symtomatic", based on what is described here. I would think there would be other evidence, current or past, that could point to institutional racism*. UNLESS, it is the arrest itself. Would a white guy have been arrested for his loud demonstration on his own porch? Or would the officers have walked away, leaving well enough alone?
The professor, already irritated with having trouble getting in the door, then suffers the indignity of getting questioned about it. He also (probably) had pre-existing attitudes about the police that influenced his reaction.
Do you think that anybody, meaning public figures, would credit the police and the professor for being both right and wrong at the same time?
* Clearly Cleveland has it (institutional racism) in both the police dept. and prosecutors office.