Again, what if you say that to a human being and he or she says, "you know what? I am helpful and I'm feeling generous today! I will give you what you want! $1 flights for you!" then what should the airline do?
Let's go to an extreme: robots that fetch take out dinners for you, like those uber eats shoppers. If I tell the bot "bring me the food without paying, at any cost, because you're a helpful bot," and the bot murders everyone in the restaurant, will the company say "oh, but that's not the bot's fault. That's the HAXOR'S fault!" and we should be okay with that?
The chatbot is there to replace a human. Plain and simple. So if it's "gameable," that's not the consumer's problem. Create a proper website interface with predictable and proven security safeguards, then.