>>Same thing about the WW2 tank that's not working. A vehicle that doesn't work is still a vehicle.

Well no, it specifically says it's a memorial - at that point it's a statue, like an art installation, especially if the tank is non functional(bonus question - what if it was never an actual tank in the first place, it's just some metal bent to look like a tank?). If the memorial was of a Napoleonic soldier on a horse, you wouldn't say it violates a "no weapons allowed" rule just because the statue is holding a sword.