The only problem that could crop up is if he is somehow prosecuted for Unlawful Concealed Carry. This moves the punishment from a misdemeanor first offense to a "wobbler" - aka could be prosecuted as a felony.
Note that he could avoid the wobbler status if he didn't carry ammo for it...
12025. (a) A person is guilty of carrying a concealed firearm when
he or she does any of the following:
...
(6) By imprisonment in the state prison, or by imprisonment in a
county jail not to exceed one year, by a fine not to exceed one
thousand dollars ($1,000), or by both that fine and imprisonment if
both of the following conditions are met:
(A) Both the pistol, revolver, or other firearm capable of being
concealed upon the person and the unexpended ammunition capable of
being discharged from that firearm are either in the immediate
possession of the person or readily accessible to that person, or the
pistol, revolver, or other firearm capable of being concealed upon
the person is loaded as defined in subdivision (g) of Section 12031.
(B) The person is not listed with the Department of Justice
pursuant to paragraph (1) of subdivision (c) of Section 11106, as the
registered owner of that pistol, revolver, or other firearm capable
of being concealed upon the person.
