The court wasn’t looking to impose a ‘bait and switch’. The airlines initially argued for a long wind-down of the partnership, to which the government objected. The position of American and JetBlue was, our IT systems aren’t set up to base benefits and mileage-earning on date of ticket purchase rather than date flown. So they couldn’t just grandfather old tickets.
That wasn’t flying as a reason to prolong the partnership. Instead what the two airlines came up with eliminating the ability to add each others’ frequent flyer account numbers to reservations.