Unless it has changed since I learned to drive we were taught anytime you rear-ended another vehicle it's your fault. Not the vehicle in front of you. Obviously the COP knew he couldn't stop as quickly as a motorcycle since he cursed that fact out to the motorcyclist. So the proper thing to do is put more distance between you and the vehicle in front of you. The COP is damned lucky he didn't injure the cyclist.
What exactly did he do that was illegal? He hit his brakes to allow another motorist who was signaling to change lanes. I don't recall that being something in the driver's manual that is prohibited. So what if the car was "way up there?" Motorcyclists (and I'm not one) have to be far more defensive drivers than car drivers. It makes sense to give the car more room.