Unless the rules have changed since the merger, my understanding is that the Sheraton (with lounge and not a resort) would be required to compensate for such a temporary (and unannounced) lounge closure.

ADDED: I just saw our lurker's reply and I would wonder whether the bolded exemption applies since in this case the hotel said that the lounge was closed due to low occupancy. Allowing this would seem to permit a hotel to close the lounge and make this claim whenever every room isn't occupied (with the maximum permitted number of guests). Effectively, except for a few nights, the hotel wouldn't have a lounge but it could still advertise the lounge and include it in listings of features and services.

ADDED YET AGAIN: IIRC I ran into this issue about five years ago, perhaps at the Sheraton Pasadena, and the resolution was that the hotel offered coupons for the buffet breakfast (I think some breakfast substitute was required) and maybe also an appetizer or drink.