Perhaps suggesting that the Japanese need more guns to be polite wasn't the best example. Japan is already one of the most (the most?) polite society in the world - at least talking about how strangers interact.
*An armed society of rational people is a polite society. And people tend to slip in and out of a rational state depending on their emotions, pride, sobriety, etc.
Example: anthropologists believe that on the whole, more polite societies typically murder each other at a higher rate than less polite societies.
"Polite" just means "in keeping with cultural norms". If it's polite to deal with disagreements, injuries and insults by pulling a gun, that's still polite but I certainly wouldn't feel safe.
If you believe that, you've never lived in Atlanta (or Japan for that matter).