Exactly - the debate is supposedly around aviation capacity for and in the South East. The North does not come into that debate.
Of course it does, the debate is also about hub capacity for the entire UK, and unless "The North" has declared UDI you're not living in a vacuumed off silo cut off from the rest of the country. <insert obvious joke on town of your choice>
They're not 100% linked of course but they're not disconnected entirely, they can't be. This is why the likes of INV, LPL and LBA et al are so keen on LHR whereas MAN which competes on a different level and is not. It's not a regional thing in parts, it's a commercial business thing. #capitalism !