pixie - "If he had done an emergency stop and the (police) car behind had rammed into him, that is entirely the fault of the car behind for not leaving enough space. I think the driver's actions were deliberate, though."
The report does not say that police car was behind the driver, rather that it was the next vehicle along the road, and was flagged down so the incident could be reported. There is no circumstance where the police car would have rear-ended the original car.
Had the police driver been within that range, he would have observed the incident first hand, and no doubt pulled the driver over for the proverbial 'word'.