Whoa there, podner, I'm a leftie and I respect cops.
From what I have learned and read, it sounds to me like Gates acted like an arrogant sorry-assed SOB who thought he had the right to treat police like dogshit just because he's a respected University Prof, etc. There are some black people who look for occasions to lash out because of past injustices. Gates needed a woman there to slap the shit out the arrogant idiot. Education doesn't give you leave to act irresponsibly.
Sure, some cops are bad and do bad things but this guy had responded to a reported break-in. I'd have been thanking him for rushing to protect my property.