That doesn't really make any sense to me, and has not been my experience with the half dozen or so of the sand diving wrasses I have kept. It would seem to me that these fish would emerge from the sand when they start to feel more comfortable with their new environment - and the sooner that happens the better IMO and IME.
Good news! Saw both wrasses this morning for a good 30 mins to an hour. Both alive! and grazing the sand bed for pods!