Why do you insist on trying to treat those who own guns as either children or criminals? Your every argument shows your support for such a priori restraints.
If children -- or anyone else -- has their individual RKBA protected, it would be by their state constitution, not the second amendment.
You're thinking the second amendment protects everyone and everything -- National Guard, unorganized militia, kindergartners, little old ladies, national defense, home defense, personal defense, handguns, machine guns, nuclear weapons, on and on and on.
Well, no wonder you sound ridiculous. Anyone would. You're trying to solve the Grand Unification Theory using formulas from calculus and geometry.
There is no Grand Unification. There is the second amendment and there are state constitutions. They protect different arms for different people for different reasons.