I mostly agree, though I'll add that a trained dog is never completely under control. A dog is still a thinking, breathing, decision making animal that seeks to satisfy itself... slave to the instincts just as we humans are. For a variety of reasons, once a dog is deployed it will not be removed until you are cuffed and done resisting. First, a dog that lets go and re-bites is the same as a cop who tazes someone after they are subdued... though the dog is just excercising its desire to bite the bad guy. Second, a dog biting the bad guy is NOT a dog biting an assisting officer. In all the excitement of a violent arrest, its not uncommon at all for a dog to bite another officer running up or even redirecting onto the handler. For that reason, some dogs are not even taught to release and must be forcibly removed from a person.
I agree that if he was purely guilty of a bicycle light infraction the use of the dog was not needed, but I also think the dog got away from the handler prematurely b/c of the late command. That being said, it can be argued if the dude just did as asked the dog wouldn't have come out the car anyway.
But again, getting bitten by a trained dog isn't all that bad