Washington isn't a duty to retreat state, but duty to retreat laws often do cover accelerating a conflict with your weapon. Going open carry, as an opposing force and as a bright white little boy, to a riot started due to racial inequity could be considered accelerating a conflict. But those laws don't apply here anyway.
But yeah, 20 minutes isn't a far distance. And he did his best to retreat even after he put himself in that situation, and I don't think there was any better decision to make besides just not being there. For him and the shit stains that attacked him.