The theory behind the idea is that if someone breaks in, the first place you will want to go is to get your kids to make sure they are safe.
Instead of having to rush to get a gun then to the kids room, and then take the kids to your safe room, or grab the kids first without a gun and take them to your safe room.
Why not make the kids room your safe room, have a defensive gun secured in a wall safe high in their closet.
If someone breaks in you rush to their room, grab the gun and keep your kids safe.
Tactically there is some logic to the idea.
I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.