"Why did you bring a God-damned gun to a presidential event?"
He could have answered, "The Presidential event was only about 2 hours of a long day of which I carry from morning to night. It made no sense to disarm for those few hours."
[paraphrased]What is the history of guns at presidential events?
How about this, "It seems that there are dozens of guns (carried by good guys) wherever the President goes. Are you accusing me of not being a good guy?"