Why shouldn't the town's cannon be operable? Doesn't the 2nd cite the reason of the state's own security [and liberty] as justification for the militia's existence? And isn't it the "right of the people" that is so recognized as having the right to arms? -- A town-cannon therefore makes much sense, as does "city AA-guns", and just imagine what would have happened to Obama if NYC had possessed city AA-guns when he buzzed the city.
Do you really want to have to store those rifles in the arms room and keep them accountable?
I have more issue with the policy on-base of depriving the general population of arms (forcing them to store personal arms in the armory).
They disable commemorative cannons so they do not have to worry about some damn fool stealing them or monkeying with them.