Don't expect your flight cancellation to be covered by PayPal Purchase Protection!
I bought a British Airlines ticket using PayPal and the flight was cancelled. BA only sent me a partial refund. I called them multiple times and the reps agreed I should get a full refund, but no one was able to resolve it.
So I tried to dispute the charge with PayPal. Their response -- our protection only guarantees that you get a ticket, and you did get one! The airline cancelling the flight is your own problem.