One of Judge Moore's arguments was that he was the highest judicial officer of the state and that he controlled the building. From what I can gather, the councilman is neither the highest legislative officer in the city nor does he control the building (our city council has a council president). However, the mayor is a highest member of the executive branch of the city--and our city's mayor physically controls city hall--so the councilman may be setting up a confrontation with the mayor.
As far as I can tell, the councilman acted on his own, without even a resolution from the city council. He seems to be daring both the city council and the mayor to take the monument down.
I wonder what office he plans on running for?