The reality is that terrorists like this guy are armed and carrying all the time, but the second amendment is for all Americans including liberals, lefties, moderates and everyone in between.
Im not advocating for violence, in fact having a concealed carry permit nearly always means the exact opposite. Someone being aggressive? You walk away and let them win. Someone tailgating you? Let them pass.
Carrying is about situations like this, between a shop owner with a rainbow flag and someone out looking for an excuse to murder someone over rage bait.