The cop was the one who had poor judgement. Seriously? Jumping on a car driving 2 mph going to a GOLF TOURNAMENT?? No, take the plate number and move on. Scottie statement - he said he proceeded as told BY police officers.
Like everyone else, cops make mistakes. Within limits, their authority and directions on the street have to be deferred to for the sake of public order and safety.
For all the cop knew, the driver could be lying or intending some form of mischief or simply be putting others in danger. The thing to do is obey the officer and then try to explain the circumstances.