Make a citizens arrest on him? I don't really care if someone is open carrying or not! Leagal or illegal, I care about their actions, if a guy is acting irrational, nervous, irate, arguing, or making gestures that would cause fear or panic than sure I would care. The guy was shopping in a store doing his own thing. If he was causing a disturbance or another issue than it would be different. If it was that big of deal you should have called the police. I learn not to screw with people unless they screw with me. By you going over to him and looking at him and his weapon you are looking for a problem in my opinion. Not very smart.