CWL is always going to fall behind in this situation as there's bigger Airports that need capacity filling. CWL has already seen expansion from this year, EXT's level of expansion wasn't great in comparison. TUI will know where it's customers are coming from and have probably realised TCX were attracting people from the same areas and trying to now spread out the capacity through the huge Southwest market. To me this is TUI flexing it's muscles and covering all areas.
Also bear in mind that TUI have planned huge expansion next year, even with the Max being delivered, this isn't on the scale that they were probably planning had the Max arrived on time and TCX still been around. That being said it could be that they've reached a cap on expansion given the level of new/leased aircraft capacity they are going to need. IF the Max doesn't come back by next summer they have either A) planned a contingency of backup aircraft or B) the planned expansion is based on a proportion of Max flying not being accounted for if it doesn't return, with announced expansion based on leased in aircraft, where if the Max does come back, it's a bonus and leasing contracts could not be taken up, or even could lead to another bout of expansion early next year.
Also bear in mind that TUI have planned huge expansion next year, even with the Max being delivered, this isn't on the scale that they were probably planning had the Max arrived on time and TCX still been around. That being said it could be that they've reached a cap on expansion given the level of new/leased aircraft capacity they are going to need. IF the Max doesn't come back by next summer they have either A) planned a contingency of backup aircraft or B) the planned expansion is based on a proportion of Max flying not being accounted for if it doesn't return, with announced expansion based on leased in aircraft, where if the Max does come back, it's a bonus and leasing contracts could not be taken up, or even could lead to another bout of expansion early next year.