Years ago, I experienced a nasty case of food poisening after eating a pork meal on a United flight from Auckland to LA. I didn't eat anything else before becoming violently ill in my hotel some hours after landing.
The Airline's response was the it couldn't have been the in - flight meal as nobody else had complained. This, of course, was nonsense, as the contamination could have happened anytime from the preparation stage onwards, but I realised I was wasting my time with them & left it there.
My point is that the airline will easily avoid any charge of responsibility where there is only one complaint.