A Private Business can “infringe” Open Carry of Firearms on their own Property.
It has nothing to do with the Second Amendment but I understand your frustration.
I also grew up Shooting Guns and I “owned” a .22 Rifle and a .410 Single Shot Shotgun when I was Eight Years Old.
Kept them in my Bedroom Closet along with the Ammunition.
No Gun Safe, no Trigger Locks, nothing.
Today my Parents would be in Jail for allowing such behavior. They also let me Ride my Schwinn Stingray to School and pretty much anywhere else as long as I was Home for Dinner. Bike Helmet, we didn’t need no stinking Bike Helmet.
Oh I forgot, my Older Brother used to carry his Rifle to High School in Long Island, NY. He was in the School Gun Club and there was an on Campus Gun Range. Nobody cared.
Sounds as if you and I were both brought up by common sense parents who wanted us to grow up as responsible citizens. I rode my bike (Schwinn also)or skated to and from school every day.
It used to be my job to clean the guns when we came home from hunting. Still love the smell of gunpowder.....in fact it’s my favorite perfume! Still hunt whenever the chance presents itself, and shoot trap.....and my pistol. Got my CCP too.