You can come up with all kinds of hypotheticals, but for a minor at home, by far the best advise is to keep doors locked when parents aren't at home, preferable with dead bolts. If a stranger comes to the door or pounds on it, the youth should call 9-11. A secure door is not going to be "kicked down" easily like they do in the movies with balsa wood doors. An untrained minor in a highly nervous, panicky state of mind, is at risk to shoot an innocent person.
I'm all for law abiding adults to own a gun for personal security if they want one, I have one myself, but we have to have limits in the interest of safety. But whatever laws you come up with there will always be exceptional cases you can cite.
and criminals will continue breaking whatever laws we come up with....No problem with keeping doors locked, but I'd want my kids to have the gun ready in the event the perp invaded even one centimeter of our home.