Shut down any city's airport, especially one for a city the size of Halifax (metro pop. 330,000), and with no international flights and no domestic flights to the rest of the country, you can count on the city's economy being wrecked in the long run.
Besides, Halifax is already a regional hub for the Maritimes. There's also a reason they built the airport farther inland - coastal fog, which happens quite a bit in the Maritimes and can be thick enough to pose a serious hazard for aircraft. This way, they don't have to close the airport as often because of fog.