I am out the other side of this issue and the only place they had issues was in LHR. Eldest who was not a drinker would always grab a random stranger and not as mentioned before ask to be supervised, but explicitly agree the arrangement only lasted to pass the entrance. He had various challenges from lounge agents but always prevailed.
And also backing up CWS' point which seems perverse, he spent many hours in CCR in JFK where they would admit him as the bar is tended.
Otherwise it was never an issue.