There's three sides to every story and we'll probably never know exactly what happened. Nonetheless, the police officer is a professional. He should be able to deal with a subject who is emotional and antagonistic without it escalating into an arrest. There is no suggestion that the professor threatened the officer. There's probably plenty of blame to go around in this case, but the bottom line is that the officer should have done everything in his power to defuse the situation. He's the expert, he's the one who's on the clock and his job description doesn't include arresting people for being disrespectful, especially in their own homes.
Edit: In response to the post about being arrested for being a putz... sure. It happens every day. And I know that when I'm dealing with the police I am on my best, most respectful behavior because I don't want to be arrested for being a putz. But it's really wrong. The police need to keep in check the understandable tendency to wield one's power when they feel disrespected. I know they put their lives on the line every day for all of us, but that does not give them any excuse to abuse their power because emotions get out of control.