I believe those pushing things by open carrying rifles while active shootings are popping up every other week in the news is making them nervous. Most don't have a problem with concealed carry, they have a problem with someone carrying a Rifle in a low carry sling with a load bearing vest full of extra magazines. There were a few kids that escaped from their parents basements who decided it was a good way to prove a point and push their rights because it was legal. Here is a picture of a couple guys shopping at a Target. Of course they are open carrying the rifle with a 30 round magazine. Rather than just say open carrying rifles, they just did a blanket open carry rule for the store.
https://www.motherjones.com/wp-content/uploads/target-2-630.jpg
https://www.motherjones.com/wp-content/uploads/target-2-630.jpg