I agree no one can prove it without testing the food. But how does one do that when they took the tray away. But if you look at when the symptoms of food poisoning it occurs 4-6 hours after ingesting the poisoned food. Don’t think this is a coincidence. The big problem I have is the lack of concern in Etihad’s part. TBH given their lack of concern I honestly cannot recommend this airline to fellow travellers