This makes little sense. If I have a quad, and Jack has a quad, and Jill has a quad, but we are all sailing as couples - then who does HAL choose to move because someone else needs a quad? And why choose one over the other. Certainly they wouldn’t leave it up to the requesting party? We have pretty much always had a quad - a stateroom I choose - and I have the reservation marked ‘no changes’ (I don’t want their version of an upgrade).
IMO, if you need a quad you should be booking early (like I do) so that you can get the cabin you want. And if HAL doesn’t want that to happen, then a quad should not be included in my choices.