Put me on the jury. Not guilty. He was protecting his property and I don't see a problem with him utilizing a weapon to chase off a trespassing agent of the government who had no right to be on his property in the first place.
BTT!
I would probably tend to be pretty lenient if the requirements were being imposed by government on his property. I would be less lenient if he obviously had chosen to be subjected to the requirements.
From a purely legal standpoint, the man was probably in the wrong. Exercising jury nullification will do little to prevent governments from unduly imposing requirements on private property.
Where are the liberal groups dedicated to protecting the right to encourage natural plants and discourage the cultivation of non-native grasses? Preventing indigenous plants from going-to-seed is quite unnatural. It's the botanical equivalent of Chinese foot-binding and should be outlawed.