For a penny-pinching organization, a new attraction needs to drive extra attendance, and not passholders showing up more often. If it isn’t going to drive extra tickets over what they could get in the summer otherwise with it just sitting there, they‘re going to hold off. It’s not just a function of opening the ride - they’d have to go spend on a big radio/billboard media buy as well.
Remember, getting UK and other driveovers from Orlando is a big part of their business. It does actually make some business sense to sit on it until those visitors are back.