wawkrk,
When KLM refused me a beer telling me no alcohol in economy I was travelling KBP/AMS ticketed with Ukraine International ..... Ukraine International serve beer(s) by the 500ml can!
I too had been in the UIA business class lounge and, like you, a beer had fallen in to my pocket on the way out, by the time they caught me drinking it on board it was too late to stop me.
Thereafter I wrote to UIA complaining that if they are to codeshare with other airlines can they not codeshare with such cowboy outfits as KLM who's level of service is appalling.