First of all, I think you linked the wrong article. Second, the Aeneid references the use of bread as a plate - in the Aeneid, they put food on the bread, eat the food, then (being hungry) eat the bread, and thereby circumvent the prophecy of "being so hungry they would eat their tables".

I can only assume the author is trying to say "the fact that the food is on the flatbread isn't because the bread is part of the dish, it's because the bread is acting as a table", with the word "sacrificial" just being an unfortunate choice of words for "disposable".