Carrying a gun is fine. 4 men walking into a busy restaurant with assault rifles, with the intent to draw attention, is a disturbance.
What proof do you have that they are "assault" rifles?
What actions did they take that "created" a disturbance?
Did they wave the guns around (An Illegal Act)?
Did they threaten someone with their gun ( An Illegal Act )?
If you are saying their presence was a disturbance, because it caused some weak-kneed people to piss in their panties, would you say that the presence of Gays in an area could also be considered as creating a disturbance? Or the presence of Blacks in an area could be considered creating a disturbance?
Gays and blacks hanging out doesn't put you in fear for your life
I would never expect to see men take assault rifles with them to make an order at McDonald's. What I'd expect is that they are going to try to rob me or kill people.
Having a handgun in a holster is convenient. It's like carrying your wallet. You have to put effort into carrying an assault rifle. If I see you with slinging an assault rifle over your shoulder in the parking then I will be expecting you to use it.
What proof that they're assault rifles? It's 50/50 as far as I'm concerned.
This store, picked for no particular reason, sure likes advertising them as assault rifles though:
AR 15 Assault Rifles For Sale