Yes sure there's no way to scientifically or rationally prove that it was the airline's food that was at fault for the food poisoning... but it's still bad form for EY to complete ignore the email and leave the complainer on read. At least they could have responded with a canned response saying ' we are sorry and we will continue to aspire to achieve highest standards in hygiene and food safety bla bla...' most retail businesses have templates of sorts for these scenarios.

Ghosting a customer email is pretty bad form, even for a local fast food chain, let alone an airline that tries to sell its level of customer care as its forte.