And a lawsuit because it is discrimination.
Although I don't condone the wages compass paid, or their actions. Firing her is not discrimination under the law. She wasn't targetted becasue of race, age, sexual orientation, or any of the other listed items that comprise discrimination under the law.
They can either state she was fired for trying to bring pulic discredit to the company, or simply terminated at will.
Although having a union will change things, most states in the US are employement at will states. That means you can quite or be fired with no notice for no reason.
It is also important to remember that there are millions of people out there working full time jobs that qualify for food stamps, its not just flight attendants or pilots at regional airlines.