He didn't say it was the answer. He posted it as rule #2. Rule #1 was posted as always treating guns as if the were loaded.
Are you being facetious?
keep your firearms locked up away from your children.
That should never be any rule number. What good is a gun locked up? And if your kids never learn how to use them then the kid is at risk when he encounters a weapon that you have no control over (the neighbor's house, a friend, a kid at school with one in his locker). This is the tradgedy of this whole story; untrained kid kills his friend because, no doubt, his parents kept their guns away from the kid. If the kid who was killed had been trained, he would have known that the the gun wasn't unloaded. The the real #2 rule is that you NEVER EVER point a gun at anything you don't intend to destroy. The OP's comment is naive. My point is train the kid. Then you can properly stow your weapons where they are accessible for defense, not locked up. I could never forgive myself if someone broke in and raped my daughters while my firearms were locked in a nearby cabinet. I train them, so they have a fighting chance.