But there are laws against harassment.
BTW, a wall which minors like to climb could end up being an "attractive nuisance" and become a liability. Check into that. Anyone who has had a child climb their motorcycle unbidden should be familiar with the term.
What I fail to understand in all this is why the guy didn't arm himself with something really good like a Streetsweeper. You pop a round into the chamber on that sucker and they'll stand up at attention and await your next command.
The Streetsweeper was classified as a "destructive device" under BATF rules when Lloyd Bentsen was Secretary of the Treasury (which ran BATF until recently). It more closely resembles an oversized revolver, with a 'wheel' type magazine, than any conventional shotgun. Loading the firearm is innocuous enough, operating it is, by all accounts a definite attention-getter. It was designed to put a lot of lead pellets either in the air at a mass of rioters, or better, to skip those shot off of the pavement into the advancing mob, usually trying to hit them in the legs. Rate of fire is fast enough to sweep from one side of an urban street to the other before the mob has advanced very far, hence the name "Streetsweeper". Facing only a couple of riot patrol police with these would generally give a mob second thoughts. To my knowledge, the weapon is South African in origin.
If you mean the distinctive noise a pump shotgun makes when racking the slide, that might be a deterrent--as might be the distinctive sound of a semi-automatic pistol slide going into battery--or if Law Enforcement came calling (wrong address-no knock warrant) you just might get yourself killed.
It appears you would bet all your chips on passive defense items, which is your right. Maybe walls, signs, and locked gates are appropriate where you live.
Criminals, Mad Dogs, children, and lunatics are notoriously bad at reading signs and following directions.
Walls and high fences are not appropriate where I live, and can create a hazard in winter. I have the means to defend myself when needed. My wife can do so as well, without the need to hide behind walls other than those of our home. To date, we have not had to kill anyone (nor have we done so).
Often, a pistol bullet is survivable, depending on placement and the type of bullet used. A shotgun at close range is devastating.
Your posts seem antagonistic toward using firearms for defense. Not everyone can afford walls, locked gates and private security.
In the case of this event, there may well have been an inappropriate use of a firearm--with tragic results. The courts will have to sort this out. They can get the facts and act appropriately.
In literally millions more instances each year, firearms are used in self defense, more often than not without requiring a shot to be fired. The mere presence of the firearm in the hands of the potential victim is sufficient deterrent.