At the risk of the huge backlash I'm sure will ensue, I will point out that any alcohol brought onboard by guests must be consumed in the privacy of their room. Not in public areas.
Alcohol is permitted on board. However, be aware that any fragile items (including bottled alcohol) must be hand-carried on board in a day bag and/or carry-on bag, the dimensions of which cannot exceed 22" wide, 14" high and 9" deep. Alcohol brought on board may not be consumed in any lounge or public area. Guests who arrive in the dining room with a bottle of champagne or wine that has been brought on board will be charged a corking fee of $20.00 per bottle.
https://disneycruise.disney.go.com/planning-center/my-cruise-plans/faqs/prohibited-items/food-storage-containers