"Gatwick as a catchment area in it's own right". What he means is that Emirates, as a quite exceptional carrier, can succeed where others fail. They can succesfully serve London from LHR, LGW and STN whereas most airlines cannot and should not even try. You scoffed at Lufthansa attempting to do this and blamed the carrier when in fact, it's a function of the market. Same goes for Aer Lingus, although I was surprised myself at that one. Delta run LGW-JFK on decades old B767s and LHR-JFK on factory new A339s with Delta One. That's a good example of the "Gatwick catchment area" vs. LHR waiting room, it's a relatively inferior offering. The growth in long haul with the Chinese carriers and Ethiopian is great BUT would up sticks and move to LHR tomorrow if they could get slots. As would Air Mauritius if they can get more slots, they didn't sell their LHR slots and given their cash situation, that's interesting.
Dedicated LGW long haul is BA, Norse, TUI, Emirates, Qatar and Icelandair. The rest would move out entirely if the market allowed them LHR access. Air India at LGW is a country mile from their own catchment area in London.