The OCer did what was in his best legal interests: he ended the conversation and left before the officer got reasonable suspicion to detain him. Of course, he could have been nicer. Something like, "It's nothing personal, but I've been told by my lawyer not to speak to police officers."
His mistake was walking back to his car. It's MUCH easier for an officer to get probable cause when you're in your car. If he follows you for long enough, he WILL catch you making a mistake. Also, when in your car, you must present your license. If he remained on foot, he wouldn't have to present it.
I sympathize with the officer, but he has to realize that our system of laws is so complicated that most citizens are positively afraid of officers. They're afraid they're going to get jailed for a law they didn't even know existed. He has to expect that people will do what's in their best legal interests and not take it personally.
Of course, this guy didn't do what was in his best interests. He screwed up when he went back to his car while the officer was watching. Screwing up his car's license plates was also a bad move.