Seriously just say "look I am Legally able to brew beer for my own consumption. Do you have a problem with that ? "
Logic, thy name is Kylito87. No need to act like a vengeful kid when the neighbors try getting the local fuzz involved. Head back to their house, be succinct and to the point, and just explain that you noticed their wandering eyes and you want to explain what they were seeing. All of this Rambo-esque behavior won't get you anything but another annoying visit from the local PD and more rumors being spread by your nosy neighbors.