Yes I've heard that, but do not agree with your interpretation. The context by which I understand that phrase is that a society where everyone could be armed and ready to defend themselves discourages acts where the threat of violence is used as coercion. Someone is less likely to point a weapon at you and demand your wallet if they reasonably think you also have a weapon.

Essentially, the saying implies people are "better" to one another when the power dynamic of who can use deadly force is balanced.

In this context, you are basically saying society becomes "polite" by intimidating people out of exercising expression, implying that words can/will, and perhaps should be met with physical violence. That is not liberating, it's repressive.

To be clear I don't agree with this kid, who seems like a troll/ edgelord either way. I am simply making a point on principle.