I wouldn't bank on it, though I imagine they'd get the ILL refunded.
The closest official policy I've seen is this:
"Reservations for dining experiences, Droid Depot, Savi's Workshop and other pre-booked experiences do not guarantee access to a park, and Park Hopper availability may change daily. We recommend Guests book in-park dining and other experiences at the park where they have a Disney Park Pass reservation. Guests can make dining reservations or add their party to the walk-up list at select table-service restaurants via the My Disney Experience app after they enter the second park, subject to availability."