Taken from the DFAT (Aussie Department of Foreign Affairs and Trade) Website.
Drinking or possession of alcohol without a United Arab Emirates Ministry of Interior liquor permit is illegal and could result in arrest and imprisonment. Alcohol is served at bars in most major hotels (although not in the Emirate of Sharjah) but is intended only for guests of the hotel. Travellers who are not guests of the hotel, and who consume alcohol in the restaurants and bars, are required to have their own personal liquor licences.
So as I said as a guest of a hotel, you may drink at that establishment without a liquor license, so again it begs the question weren't these guys guests of Etihad and as such were allowed to drink with them?