By the description provided, #1 is pretty clearly in violation of the regulation designed to prevent interference with a hunt, at least IMO. See excerpt below. But proving it would be problematic. Meanwhile, it would NOT be as simple as dropping a shed in next to the fenceline to prevent him from shooting within 200 yards of a building, as the building needs to be inhabited by people or livestock. See second excerpt...
Clearly, the guy is a jerk and the dilemma is how to handle it without escalating it to a potentially dangerous situation. I think Skip is right, the situation may right itself after the guy learns that his shoot off did not prevent #2 from getting a buck yet that morning and/or he just gets tired of it.
From the IDNR website...
B) intentionally creating a visual, audio, olfactory or physical stimulus for the purpose of affecting the behavior of a furbearing animal, game bird or other game with the intent of obstructing or harassing another person who is lawfully hunting or trapping.
Also from the IDNR website...
PROHIBITED HUNTING NEAR BUILDINGS You cannot discharge a firearm, or shoot or attempt to shoot, a game or furbearing animal within 200 yards of a building inhabited by people or domestic livestock or a feedlot unless the owner or tenant has given consent to do so. Feedlot means a lot, yard or corral where livestock is confined for the purpose of feeding and growth prior to slaughter. Pastures, hayfields or cropfields where animals are allowed to graze are not considered feedlots.