Philip
On Moderation
And travel to/from the Airport, I presume you mean. Well they certainly shouldn't be travelling from Bolton, since the TPEs are generally set-down only at Bolton, heading south. As to Preston and Lancaster, well Preston has two alternative services to the Airport per hour, and Lancaster has one. (Occasional ex-Windermere services don't currently call, but I'm sure that situation is capable of being sorted out). How many trains to the Airport do the folk of Preston and Lancaster need?
I accept that passengers probably travel from Carlisle to/from Manchester Airport, but there are Virgin trains available as well as TPE, and an easy interchange at Preston.
And likewise, there are many other services between Wigan and Manchester to make an easy change in Manchester for the Airport. Ideally capacity should be improved in Manchester to allow all services to continue running as they are, with the additional Connect services to come, but if a Preston-Airport had to be diverted to Victoria to make space, then it makes the most sense to divert the Cumbria service.