He'd probably comment that he probably has individual buildings with that many people in 'em, and we don't have the the same problem with weapons in an urban environment since we are so sparsely populated.
Seriously, though, he would probably just claim that there is absolutely no similarity in the two environments, and what happens in one has no bearing or relationship to what happens in the other.
(To some extent he'd be at least a little bit right. Start piling people on top of one another and the social interactions do get more strained. When one is dealing with an area where a few city blocks has the population of our entire state, the interactions are just different. I spent a lot of time in NYC when I lived back there, and the "crowding" does make a big difference in the way people interact with each other.)