True Blue you're failing to see how the dynamics of this market work.
Compare the number of non stop far east and Chinese routes out of CDG/FRA/AMS and then LHR. London lags behind hugely, now by your impeccable logic, if they can't get LHR, they'll be at LGW. How come so many of them aren't in London at all?
LHR works well due to a critical mass of connections due to legacy BOAC/BEA and empire routes history as well as being round a whole lot longer than LGW. Hence your concept of a level playing field in certain markets os flawed as the existing market is so skewed to LHR.
Also, your assertion that LHR has a monopoly on business travel is quite far from true.
So you can regulate and disadvantage some at your discretion, or allow the market to function freely and support it. Either way, China fly A380s from Amsterdam, not Gatwick. Gatwick is in London and has slots. Worth considering why the capacity is in the Netherlands.