They can announce all they want. From the school side we need to know where we need to backfill and not sit around to wait for decisions and moving targets.
We need to go out and hit the portal for good players and not assume so and so will be back or so and so is still deciding or negotiating on multiple fronts. The best we should do is to give a player a courtesy "right of refusal". If you are coming back for sure, these are the terms and sign here. If you are undecided, want to test portal water or go pro and need time, fine, we will go find someone, when we are ready to commit to that player, we give you a chance, 24 hours, to decide if you want to hold your spot by signing, if not, your spot and associated NIL will be allocated away from you. I think that is fair.
Once signed no more negotiating and backtracking without penalty.
Say you signed a NIL agreement with XYZ car dealer for 500K, if you change your mind and go to another school you should suffer some financial consequences for backing out.