Man honks at oncoming driver coming into his lane, cop near him thinks he honked at him and gets his ego hurt. Pulls him over for "improper use of horn" and then when he tells argues, cops insist on doing field sobriety tests (which are optional in all 50 states and can have no consequences for refusing) telling them to skip that and give him the breathalyzer, which they claim they can't do.
Many people get confused about field sobriety tests (FSTs) and think you have to take them. No, they are optional and they can't retaliate for refusing. FSTs are of absolutely no benefit to the person, as they serve ONLY to build probable case and are 100% subjective. The "implied consent" when you get your license does not apply to FSTs since they're subjective, it applies only to chemical testing. You can't lose your license for refusing an FST.
The reason for them to do the FST rather than breathalyzer is because they wanted to use it for probable cause to arrest him for DUI, which refusing the FST forces them to build probable cause without it.
That's why so many are arrested for DUI when sober, cops claim they "observed" enough to give them probable cause in the FSTs even though they blow zero.