Queues are in nobody's best interest - least of all the airport (whether LBA or anywhere else) regardless of where those people are flying to. Airports make money from passenger spend in the terminal. Time spent in queues means less time in those shops restaurants and bars. Flights to the beach have more passengers so more money making opportunities (particularly the once a year family holidays or groups.) A London route is often seen as a "jewel in the crown" but business travellers buying a coffee if you are lucky arguably don't add much to the bottom line.
If codeshares are developed, I wonder if the route is more likely to attract connecting traffic rather than P2P business traffic. The train offers a more frequent alternative to central London (of course not all businesses are in central London.)