We do get used for target practice alot by military planes, but usually between Natchez and Baton Rouge (from Naval Air Station in Chalmette). They use us because of our slow speed and relative size to naval targets.
I'm not sure of the normal incidence of crop dusting buzzes, but I personally have experienced the naval buzzing a number of times. Let's just assume this jerk was showboating and will pay the price for it.
This was no accident...
Or he was in a hurry and didn't want to show back up wherever with full tanks and decided to be funny. I've heard of pilots dumping their load and telling the farmer they dusted. If this is a kind of salt-water like they are saying, the farmer probably would never know.
Either way the guy needs to be shown the errors of his ways, perhaps an hour or two alone with the people he sprayed.
I assume the Navy aircraft don't actually drop anything on you, nor shoot at you. This bozo did drop/spray something on both the barges/tug, and the pleasure boat.