Very interesting. Mark that as one point for my lack of imagination. It might be tough to establish that the consumer entered into that contract knowledgeably,

Very interesting. Mark that as one point for my lack of imagination. It might be tough to establish that the consumer entered into that contract knowledgeably, but there are a lot of more important terms in that same document -- so the airlines might have some powerful supporters with a vested interest in the validity of those contracts. Still, tortious interference presumes an existing contract, from my expert legal reading of Wikipedia. If a customer enters the contract with a preexisting intention to breach, I am not sure you can accuse the site operator of interference before the fact.