Actually, the problem is consistency. My son also 16, gold and flying in J gets easy access everywhere but Dubai. So I don't quite get if its a system wide rule or station dependant. About half the time he gets in in DXB too. One time they said "no" he went and got someone at the gate to escort him in and then the guy proceeded to enjoy the free flow alcohol for a couple of hours.
Twice they have given him permission to take a quick shower, eat and vacate the lounge within an hour. The agent kept his passport both times they allowed this.
Ask inbound FA if there is anyone in Y with same destination.