It would seem to me that one might thwart the charge if wearing a sixgun while dressed in cowboy(girl) regalia, such as one might do to promote a coming rodeo. One could claim that if police are exempt from D.O. charges (due to the presence of a gun) due to their special clothing (unform) then one might also expect a firearm to be carried on someone dressed as a cowboy.
But given the vagueness of the statute, simply riding a horse down any street might violate the law by creating a "disturbance".
BillCA in CA (Unfortunately)