Back 20 years when I used to ride to work every day, at the end of each month I would almost always encounter a police check point as I approached Bang Na on Sukhumvit Road. It was constructed in such a way that the inner two lanes were blocked by busses, lorries, taxis and cars and there is no U-turn for some distance. The scam was to "catch" motorcyclists in the outside lane with no excuse and pocket the fines.
The sort of behavior by this cop is reminiscent of the scams we had to endure, which are often precluded by a "clamp down" of some type. Giving chase was unnecessary and potentially dangerous in this case.
And before anyone askes, I ALWAYS wear a helmet.