Reminds me of the San Diego incident just a few years ago.
There was a ringer going through the security check with a fake grenade in his open carry on bag. It had a sweater on top of some of the other items in the bag. He apparently got through the check point with it, and then some dirtbag stole the bag and boarded her flight. As she was stowing the stolen bag in the overhead, the dummy grenade fell out into the plane aisle. Jailarity ensued.
There is a CA Penal Code section that prohibits even dummy grenades at airport "Sterile Areas":
171.5. (a) For purposes of this section:
(1) "Airport" means an airport, with a secured area, that
regularly serves an air carrier holding a certificate issued by the
United States Secretary of Transportation.
(2) "Passenger vessel terminal" means only that portion of a
harbor or port facility, as described in Section 105.105(a)(2) of
Title 33 of the Code of Federal Regulations, with a secured area that
regularly serves scheduled commuter or passenger operations.
(3) "Sterile area" means a portion of an airport defined in the
airport security program to which access generally is controlled
through the screening of persons and property, as specified in
Section 1540.5 of Title 49 of the Code of Federal Regulations, or a
portion of any passenger vessel terminal to which, pursuant to the
requirements set forth in Sections 105.255(a)(1), 105.255(c)(1), and
105.260(a) of Title 33 of the Code of Federal Regulations, access is
generally controlled in a manner consistent with the passenger vessel
terminal's security plan and the MARSEC level in effect at the time.
(b) It is unlawful for any person to knowingly possess, within any
sterile area of an airport or a passenger vessel terminal, any of
the items listed in subdivision (c).
(c) The following items are unlawful to possess as provided in
subdivision (b):
(1) Any firearm.
(2) Any knife with a blade length in excess of four inches, the
blade of which is fixed, or is capable of being fixed, in an
unguarded position by the use of one or two hands.
(3) Any box cutter or straight razor.
(4) Any metal military practice hand grenade.
(5) Any metal replica hand grenade
Goes on to include plastic replicas also. But, that's Califonia for you.