So I am probably in the minority here but.....what would happen if you went ahead with your competition plans as usual? Call their bluff if you will. Make them enforce their interpretation of the law and then use it for good PR....something like "Long standing Idaho State Fair tradition cancelled due to law interpretation". That will get many more people/politicians to take notice and you have a better shot at getting the law changed.
Because he respects the law and doesn't want to be a jerk? We didn't have to do anything here to get the law changed without a single negative vote anywhere in the process. Why not take the high road?
Absolutely take the high road. What I am saying is make the responsible agency cancel the homebrew comp via some sort of specific written documentation. That plays much better in the media than a bunch of homebrewers deciding not to have it. Besides do they "really" respect the law when it clearly says only "native grown products" can be used. That seems pretty cut and dry...only Idaho hops, barley, yeast and water can be used. Pretty ridiculous