This may sound stupid, but maybe they're delaying the opening until whenever they get new maps in. I believe the current maps in use are good until today or tomorrow (you know how Universal prints the hours of operation for the whole week on their maps), and the maps in use still have no Springfield artwork, and still a star where the spinner should be saying "Coming Soon: Kodos & Kang Hurl & Twirl". It seems like the two would be irrelevant but you never know. Maybe they're just waiting on new maps to be printed so they can give the ride proper billing and update the artwork around the World Expo area.
Just my far-fetched guess.