I wanted to add this little point:
RCW 9.41.270 was originally HB123 in the 1969 Legislature. There was two provisions to this law: An intimidation ban and a 500 foot within a public building ban. The "Exceptions" provision was meant more of a manner of exempting from the 500 feet ban more so than the intimidation ban, but it was kept nonetheless. It also originally exempted CPL holders (Which would have made RCW 9.41.270 a moot point for CPL holders and turn it into a licensed open carry state).
The locational ban was removed due to concerns that persons would get arrested for peacefully carrying their firearms near public buildings, and the licensing exemption was removed as well due to the locational nature of that exemption. The idea of requiring carry permits for carrying a handgun openly in the state of Washington at that time was an unthinkable concept to the Legislature at that point.
What we were left with was basically panicked political compromise between the House and the Senate, who were trying to pass a ban as quick as possible to prevent the Black Panthers from storming the Washington Legislature.
That being said, the Legislature never intended for peacible open carry to be banned. They were targetting radical political groups. Period. Regardless of what Spokane Transit or certain police agencies in the state, that was their intention.