The one I linked specifically mentions shooting afterwards for kids as young as 7…
But yes if guns are at home they should be locked (and really locked, like a trigger lock plus a safe that’s set to something besides 1111, holy crap you’d be surprised at how cavelier some people are) and totally inaccessible to kids. Teaching single digit age kids about guns is not a substitute for that, but of course I’m not saying you shouldn’t teach your kids that they shouldn’t touch guns and what they can do.
And teaching kids about guns will not solve the serious gun problems in America. The gun problems unique to America that pretty much every other industrialized nation has figured out already. And it’s a horrible tragedy that stuff like “the heroes program” to teach preschoolers how to deal with active shooters is necessary in this country. All to please gun nuts.