As far as the customer goes, Qantas stuffed up the catering. The customer doesn't, and shouldn't , care that it was DNATA that actually provided the catering service. The company I work for outsources a lot of production to toll manufacturers, or partners, but if the wrong thing ends up in customers hands we're not going to publicly point the finger at the toll manufacturer and say "oh look it's all their fault" (Privately, of course we'll either sack the manufacturer, seek compensation from them and/or work with them to make sure it can't happen again, depending on how important they are).
That sort of blame shifting only works for politicians.