Here's the deal, the same way there's physical 'Use of Force' continuum, which dictates how a cop can respond to an individual, there's likely a traffic use of force continuum. That would specifically say, 'In circumstances with X conditions (threat to bystanders, failure to yield to lights/sirens), you may use spike strips/pit maneuver/etc.' However, throwing coffee is NOT on that list. As I mentioned above, throwing coffee does NOT fix the problem.
Doing anything that's on the specified list of 'how to handle a traffic violation' is going to be better than, 'OC riders' or 'throw coffee at riders' or 'shoot rider with a taser'. There are just certain things you don't get to do when it's your job.
I have attended arrest and firearms training (PC-832), and was a patrol office for the USN for a period of 3 years ('85-'88). Please note that I did not say I condone that officer's actions. I said I understood them.
Any time a LEO has to deal with a group which outnumbers them, that's a scenario any LEO wants to avoid.
In any scenario, in order to control the situation, the LEO is ALWAYS authorized to escalate the level of force applied one step past what he is faced with. How do you classify 12 bikes at 30+ MPH, against a pedestrian?
Here you have a group of ~12 riders who are operating in a dangerous manner. Granted, some more than others at that particular
moment. What occurred more than roughly 30 seconds on either side of that clip is open to interpretation. What the LEO could see that you and I did not may have influenced his choice.
You and I would both not have been in that situation, and would not have the opportunity to get befouled with a latte. We both have more common sense than that. Immature behavior of a group, in the face of authority, and a response that was obviously immature.
We could spend the time getting offended, and start talking about civil rights, etc. personally, I think there's a credible case for assault in this. But I would seriously hope any filing that may occur would get laughed out of court.