What about the one premium drink lounge rule? Could it be the other people you did see could have been drinking house wine or beer? This is no excuse for the bartender to be rude. Did you tip? Again no need for the bartender to be rude. I still would not complain. You are going to be told to pound sand. There is employee shortage right now due to Covid. Be happy the lounge is open and you got inside. You can find a internal message at Delta asking employees to volunteer in the Delta Lounges. I am sure there is shortage as well at Centurion Lounges.