The way i see it my dude, there are two checkboxes for this event, meeting both criteria. A being this gambling age and B being the legal age for consuming alcohol.
Do they meet the age requirement for gambling? Yes? Good.
Do they meet the age requirement for consuming hard drinks? No? Then not possible my dude.
Because in this instance, it all falls under the Hotel's policy. The hall of Chaos is held within the Hilton and they have a different policy compared to grounds held within the convention.