I'll say it louder for the people in the back, an emotional support animal is literally just a pet. Jet Blue does allow trained service animals and you can bring cats and small dogs in the cabin provided they stay in their carriers.
While her cancer could have come back due to stress, this stress is purely of her own creation. Follow the damn rules. God damned emotional support spider bullshit.
Not that I'm ever on the side of a soulless corporation, but gods above, there has to be a line.