Presidential Event Gun Toter Gets Confronted by MSNBC's Matthews

I don't mind freedom of speech, but I do mind very much when a crazy (for lack of a better term) decides to carry a gun to a presidential event.
That's exactly what was reported earlier today, and MSNBC's Chris Matthews was right to confront this nut.
Just how cold-blooded was this guy? Here's a small snippet of the interview as the Huffington Post reported:

The segment grew more and more heated as Matthews repeatedly asked Kostric why he came to the meeting wearing a gun. "Well, why did you bring a gun to a Presidential event today?"
"That's not even a relevant question," Kostric said, shrugging. "The question is, why don't people bear arms these days."
"Okay, you bought a sign that said 'The tree of liberty must be watered with the blood of tyrants' and you're carrying a god damn gun at a Presidential event. I think those things make people wonder what you're about."
Kostric for his part, was unrepentant, and maintained that he was there in a totally non-violent capacity. "No one from New Hampshire was alarmed. Maybe some of the people they bussed in from Massachusets were alarmed. But we're not really concerned about them."

I find Kostric's answers to Matthews troubling. How was one NOT to think that he had something other peaceful intents in mind by virtue of his carrying a gun to a presidential event.
How are we NOT to assume that given the opportunity, he wouldn't pull his gun and fire shots at the president?
In the paranoid times we live in, we cannot afford to be lax when it comes to one who carries a gun to a presidential event.