The Rally was not held in a gun free zone. The gun grabbers makeup the law as they go.
Check it out:

Blaming a rally by a group of legally armed Second Amendment advocates at the state Capitol in Olympia Thursday, Washington’s Lt. Governor ruled Friday that guns are now banned from the chamber.

The rally of some 200 gun rights activists on the steps of the Capitol building Jan. 15, was a continuation of the vocal opposition to the state’s background check ballot referendum, I-594, passed by voters last November. However, when the protest spilled over into the public gallery, there was an altercation between an open carrier and a state police lieutenant that ended with threats of removal and arrest.