Just a couple of points that may not set the world on fire, but I'll make them anyway.....
1: Last time I was in HKT (as pax) I had my bottle of water removed when entering the terminal through the security point just inside the door. I then bought another bottle which was removed at the main security/passport area. Finally I purchased another bottle in the airside area to take onboard, which was then promptly removed at yet another security bag search at the entrace to the aerobridge, so this person may well have tried to take some onboard only to be thwarted by over zealous security.
2: I'm not sure if HKT is the same, but if a
VB aircraft uplifts potable water in DPS it is not suitable for drinking and the tank must be steralised on arrival back into Oz. Maybe this prevented free water being given?
I suspect there is a lot more to this that wasn't written in the pax complaint. After all, nobody mentions the stuff that doesn't show them in the best light when making a complaint.