I don't know about your area but in just about every place I've ever lived that sort of thing falls under "disorderly conduct."
His getting a ticket should tickle him pink. Get hit with the disorderly conduct charge and they'll typically arrest you, tow your vehicle (just for giggles), take you to the station for booking, charge you, and have you appear before a judge to enter your plea and you'll either be released or have to post bond. That's considerably more inconvenient than handling a ticket.
And, disorderly conduct can constitute an awful lot of things - use profanity directed at the officer, make hand gestures, fling and flail your arms/legs (without making contact - you don't want to do that) - bunch of stuff. Seriously.
You want to behave yourself. This guy will find that out, I suspect.
All of what you mention may be true, but it is also a convenient 'catchall' for screwing with people. The Trooper isn't exempt from a one finger salute.
How is society served by issuing a ticket? How is it safer?
This cop would be better off patrolling for real criminals instead of trolling for finger flippers. But I guess that ticketing finger flippers and court appearances is a hell of a way to earn a living and not have to bother with real and potentially dangerous criminals.
I don't know about your "area" either, but I'm assuming it's the U.S. and not Canada or Mexico..
And every place I've ever lived that sort of thing falls under the Supreme Court's decision that it's "FREE SPEECH"..
( That's in the Bill of Rights, 1st amendment.. )