I'm not familiar with NC law but most of these open carry states the police cannot stop you simply for carrying or even ask for a permit.
Not sure where you get that idea.
The police will most definitely stop you and make sure you are legally allowed to carry a weapon if you are displaying it openly.
People seem to be really confused what open carry actually means. You can not walk around with a pistol in your hands. If a cop knows you have a weapon concealed or open carry they will tell you to either leave it holstered or let them remove it while they run your ID.
Just because it's an open carry state does not mean you can jump out of your car with a gun in hand when confronted by police.
In an ideal world this would not be a death sentence but in USA world it probably is. When the police here have their guns out it's time to stop fucking around unless you have a death wish. This guy had mental issues and was high. He may have panicked and not even realized he was still holding his gun.
Police need to come up with better ways to deal with people. I'm not sure what people expect them to do in situations like this though. They can wait till he aims but then one of them or a bystander is taking a bullet.
Trying to break the window and force him out of the car seems really dumb, I think if they let him sit there and realize the full situation he would have given up peacefully.