From NRS 202...
(b) “Public building” means any building or office space occupied by: (1) Any component of the Nevada System of Higher Education and used for any purpose related to the System; or (2) The Federal Government, the State of Nevada or any county, city, school district or other political subdivision of the State of Nevada and used for any public purpose. If only part of the building is occupied by an entity described in this subsection, the term means only that portion of the building which is so occupied.
Cashman Center is not part of the Nevada System of Higher Education.
Cashman Center's convention hall is not "occupied" by the Federal Government, State of Nevada, or any county, city, school district or other political subdivision of the State of Nevada. Hence, the convention hall - during a gun show - clearly does not meet the legal definition of "public building."
They cannot legally prevent concealed carry.
Even if this was a convention room attached to city hall, it would not qualify as "only that portion of the building which is so occupied" during a gun show, wedding reception, trade show, etc.
Ken, how would you argue that a convention hall, being used to host a gun show, is being occupied by the government or school system?