When Station 51 is called for the gas leak, the voice that acknowledges LA is not that of Captain Stanley, or anyone else in the crew.
As Johnny is climbing down the spine of the hanging sign in an effort to secure it, a line can be seen to the right, already in place.
Moving the crane isn't an option. To do so the outriggers must be retracted, with the boom high in the air in the wind carrying a heavy load the crane could quite easily topple, so this wouldn't even be considered.
When Cpt. Stanley asks the crane operator if he can lower or raise the swinging sign, the operator states that he can't do either because of a busted hydraulic line. All he had to do was move the entire rig either forward or backward to get the swinging sign our of the way.