Doesn't sound crazy to me, though I would perhaps expect a bit more. Job interview question!

It seems to be 50%+ cheaper than the champagne. Take off tax and bulk discount, so maybe difference between bottles is net 2e?

10 million pax, say 15% discount to exclude Y only flights (?), 15% pax in business, maybe 30% have champagne any given flight (?) so that would be in that range...