Why does every stupid person mean that the hobby is going to be ruined for everyone?
THE SKY IS NOT FALLING!!!
There's always going to be people doing something stupid, but this is probably not a violation of §91.15 "Dropping objects":
No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in flight that creates a hazard to persons or property. However, this section does not prohibit the dropping of any object if reasonable precautions are taken to avoid injury or damage to persons or property.
Never in a million years I ever thought that I would be defending a gun nut. But if he is a responsible gun owner in the woods where discharging a gun is not illegal and he takes precautions to avoid any injury or damage - then what is the problem? Take the gun off the drone and you're OK with that? You don't see what he is shooting at - it could be a target in front of a dirt berm at a shooting range. You don't know that there aren't any safety precautions built into his system. You know nothing but the sensationalist fear mongering, and you should know better than to add to it.