Strangely, the OP says nothing about the passenger's behavior being related to alcohol service, although it appears that OP made the leap.
Bottom line is that some people are simply jerks. Whether EK ought to stuff the galley full of hamburgers or provision three of them is irrelevant. Once learning that there is no more hamburger, it is not as though the crew can send out for more meat, so time to shut up and sulk in silence.
EK will do nothing here as this simply turns into a debate about how many hamburgers it ought to carry.