Again, what does any of that have to do with responsible parenting?  

This issue here is a parent who left a dangerous item within a child's reach.  It doesn't matter if that item is a gun, a knife, a bottle of pills, or a box of matches.  All of them can be harmful or even deadly if a child gets a hold of them.  The parents (regardless of what culture they're into) are the ones responsible for securing those items.

If a kid gets a hold of a gun, you cry, "It's the gun culture! The gun culture is to blame!"  But if a kid gets a hold of anything else, then it's oh well, just an unfortunate accident.