Looks like the rider had a lot of room to maneuver around the paddler... Simple high-line would have worked, or he could have even pulled off. The paddler was clearly in the way and cut the guy's line off, but the rider was the more fucked up party here.
Surf etiquette aside, basic human etiquette dictates you shouldn't slam into another person with a huge dangerous longboard- regardless of how clueless the person might be. A regular wave surfed purely for fun isn't worth fin stabbing someone's eyeball out.
I guess technically that makes the rider more of an asshole than a kook though...
Kook = Paddler