Might I suggest that these timings were purely indicative of a sample schedule, should planning be approved, and therefore they have no relevance to any actual service, which will depend on the relevant operator willingness and airport cooperation at the time.
I second what dj6 has already said - utterly pointless to fly to deepest Essex when going up against a train service that is largely under-used.
Remember - this route would have to survive on its own merits, whereas the train will continue to exist regardless, as Carlisle is on the way to somewhere else. Much easier to take advantage of that face and stop pretending people will want to fly to somewhere and then spend an hour to get into London to save what - an hour?