Lol, are they confusing chickens with demons and ghosts??? The only thing that salt will do is kill snails, slugs, and the grass / plant life in that area for a few years...Last night they put a line of salt along the border of our drive way - without saying anything. They told me a while ago that they heard chickens don’t like walking though salt. I don’t know if this is true either!
If they put the salt on your property without your permission and it starts killing plants (it will) then you could actually get them for property damage potentially.