I think the poster who you were replying to was commenting specifically of the legal right to compensation. As you have pointed out, it is advertised as complimentary - legal definitions vary but effectively BA could argue in court that be definition they are saying it has little of no value in itself (whether you agree with that or not- but that’s why marketting often uses the word complimentary). It is unlikely if you went to court you would get any compensation. As pointed out, EC261/04 only covers duty of care including food during the delay itself- not during any flight.

This is oppose to customer service recovery, which the OP should absolutely receiver IMHO. Personally, knowing the lack of catering services at that airport I would bissue I personally would have purchased something to take with me and then put it in my claim rather than trying to get Avios, but that is easy to say in retrospect.