Just riding away in a different direction seems way less fuss than potentially escalating to that level or beyond. The above poster is correct - even blowback from pepper spray is no fun sometimes.
Way less fuss really! The timing of this particular situation negate's your wishful thinking. Things like fight or flight and sensory deprivation can take over. The man never dismounted his bicycle. If possible you get off of your bicycle and stand upright with one hand on the seat and the other grasping the handlebar. I have watched YouTube videos and seen people who are mounted on the bicycle thrown to the ground at the delight of the aggressor. In the videos were the bicyclist dismounts the bicycle and stands upright not so much. I have seen two videos were the motorist slams on the brakes coming to a stop then gets out of the truck and rips the bicycle from the downed bicyclist and throws the bicycle into the bed of the truck and drives away. Chemical sprays are more effective on animals because they aren't aware of the danger. The only chemical spray I carry is the most effective and long distance one. Bear spray 14oz can with the sleeve that fits a water bottle cage.
I read the story and it was quite apparent to me that the motorist was angry before he encountered the bicyclist. The bicyclist escalated the situation with the Hawaiian peace sign. I won't escalate any situation unless they make it necessary.