I'm no attorney, but maybe a speed bump in the Mayor's plans?
RCW 9.41.300: Weapons prohibited in certain places ? Local laws and ordinances ? Exceptions ? Penalty.
(2) Cities, towns, counties, and other municipalities may enact laws and ordinances:
(b) Restricting the possession of firearms in any stadium or convention center, operated by a city, town, county, or other municipality, except that such restrictions shall not apply to:
(i) Any pistol in the possession of a person licensed under RCW 9.41.070 or exempt from the licensing requirement by RCW 9.41.060