Costas is a PC tool. He's not really talking about the "gun culture" - those of us who frequent this board know what that is and are almost universally members of it. As has been stated, we're generally quite anal about safety, responsibility, and being non-confrontational. We also tend to be among the most law-abiding demographic in the culture.
No, Costas is really talking about the "thug culture." He can't call it that because the term has socio-economic and racial overtones that are strictly forbidden in PC speech. The thug culture is characterized by violence as a response to virtually any slight or insult, real or perceived. Often, but certainly not always, guns play a role in this violence. But that's strictly secondary to the cause of the violence, and has nothing to do with the "gun culture" as we know the term.
Of course, lumping the two together is a win-win for the left: they avoid calling out "thugs" by name (a PC no-no), and at the same time associate folks like us with the likes of them, strengthening their case for more stringent restrictions on firearms across the board.