> This would be fraud.

I think 'fraud' has a specific technical definition - it requires 'intentional deception' or 'misrepresentation' or something similar depending where in the world you are.

If they decide to cancel your flight for business reasons and genuinely weren't planning to when they sold you your ticket you can argue that you should get your money back under consumer rights about paying for services provided and maybe contracts I don't know, but it doesn't really make any sense to claim it's 'fraud' - there isn't the deception or misrepresentation required.