As far as I know, the lounge policy is left to each hotel - some are open only mornings & evenings (business type suburban properties), some open all day (downtown) and some even open on weekends. So you are going to find a mix but I don't see why they should comp you drinks, etc when they are not open. Maybe there isn't high enough of a demand at that hotel to have it available all day/night. If there is a Marriott standard, then it certainly isn't followed since I can name numerous exceptions.