Is anyone really surprised that the Cambridge police couldn't define what constitutes disorderly conduct?

One simple question about what Professor Gates did that made it disorderly conduct and the mouthpiece at the microphone defers to the lawyer who hems and haws for 5 minutes about how it's really tricky without ever giving a straight answer. News conference epic fail. Why not just be honest and say, "Sergeant Crowley wanted to arrest this guy for being too uppity?"