It’s Texas — you’d sure think they’d all know.
A shotgun in the trunk won’t do a lot of good if he gets accosted while driving and surely he isn’t expected to take the shotgun along with the pizza to every household. Can he carry an imitation gun in the passenger compartment itself? (Usually an attacker who sees one will not wait to check it out, but will flee.)
I believe he has to be 21 to carry a handgun in Texas unless he’s a member of the military. (he’s not)
"Texas has no laws regarding possession of handguns, shotguns, or rifles by persons 18 years or older without felony convictions; a rifle, shotgun, or other long-barreled firearm may be carried openly, however, a permit to carry is required for handguns (issued only to those 21 and older), and they must be concealed.
"However, to PURCHASE a handgun, you must be 21 or older in every state, per federal law in order to purchase from a federally licensed dealer. You can, however, purchase a handgun at 18 in a private sale."