How did your ego get so wrapped up in this? How does plumbers doing gas repairs become such an insult to you? Whether someone in the building is authorized to call the plumber directly, or if the phone call is handed to a maintenance man to make, what difference does it make, if an expert is needed, then someone will call a plumber.
City property they will likely call the city maintenance dept which whether you like it or not may or may not be able to do repairs etc and make that necessary determination. Even the one patrolman and a dispatcher small town PD near me do as much.
The maintenance department is most likely called in the case you mention because they usually have the needed information about the building INCLUDING WHERE THE GAS LINES RUN INSIDE AND OUTSIDE OF THE BUILDING! {that the contractor will need to know if called and hired} If you are an actual contractor then you would know it, understand it, and I would not be wasting my time explaining it to you which makes me think you know not what you say you do. I think you specialize at installing Al Gore Commodes myself. Seem to remember a discussion on this.
The contractor likely would not respond to the emergency as an emergency responder at least not a general plumber. The fire department and gas utility would be first responders along with maintenance dept because the FD Captain would discuss next steps with them before leaving.
Bye Now.