As Moonbrook's mayor, you have access to the printing press that's been only barely used in years. It's not a difficult affair to swing public opinion against the Defias; the public was already dissatisfied, and the Defias, who were known to cause trouble, are hardly doing anything to appease the public. The next time the Admiral comes near your office, he is swept away by a crowd. You never see him again.
Use your new power to conquer Westfall once and for all. Use the downfall of the Defias to align Moonbrook with Stormwind again. Remain neutral. Just keep your hold on the town. Use the Defias's absence in the area to learn what really happened on your way into Westfall.