I find it very hard to believe the serving staff know what you are flying.   I have been in the Sydney  lounge as an F passenger (paid not even award. 

 ) and just about had to beg for another glass of bubbly and was in as a  WP J passenger a couple of weeks ago, where the lovely Dubrovka was walking around filling up glasses on a regular basis. Service and frequency of drinks seemed more a function of how busy the lounge was.  Maybe there is someone in charge in the Mel lounge who has decided to enforce the guidelines and customer care is presenting a united front.  Hopefully behind the scenes a message might go to the frontline to say they are being a bit cough about the rules.....