I would like to know that they reserve such tactics for violent offenders, but there isn't much to go on, couldn't find much besides inflamed opinion on that incident. Certainly it is hard to justify that result for a minor traffic infraction, but if the guy causes someone else to wreck then??
It looks like the cop was going about 3mph at impact, might have actually stopped. You can see the rider is aware of the cop car fairly early, he moves left, cop matches, he cuts back right, cop matches, bam.
The fact that they were converging really cuts the decision time down, still a bad decision by the rider to get in a game of chicken with a squad car.
Here was a crappy deal: