Upset at being honked at Cop declares horn use "road rage"

I am impressed with this motorcyclist's ability to remain calm, and attempt to reason with this angry police officer!

A motorcyclist was frustrated by having to wait behind a non-moving car at a round-about, so he honked! The driver of the car turned out to be a police officer who claimed his texting-while-driving was in the name of public safety. The cop then proceeded to educate the motorcyclist, evidently honking is "road rage."

Anyone here from Colorado, where the video took place? Is using a horn illegal in Denver?