technically, a minor can own a handgun. inheritance is one of the exceptions. Right now the guns are owned by estate of the man. Whoever administer's his estate is under a duty to handle things as the creditor's and heirs' best interest may be. The son is maybe the only heir. He can't administer an estate until age 18. Between funeral bills, expenses of last illeness and other debts the guy left, the guns may have to be sold. An heir doesn't automatically have a right to take property in kind. Especially where debts outweigh personal property. We don't know what other assets or insurance the guy left. The mother or guardian of that child will probably need funds to raise the boy. It is probably too early to say what should be done with the guns.
If there is any particular collectible among them, perhaps a grandfather will buy it from the estate and store it away for the boy when he is of age.
Now even though a minor can technically own a pistol, it doesn't give him the right to possess it or use it, except in accordance with some very strict rules. We can "own" things that we can't possess or use.