You gotta be kidding. Tons of cases where pilots have been reprimanded/fired since no protection because of no union.
Don't work for them if you care about your career

e.g.
An administrative law judge has ordered SkyWest Airlines to rehire a veteran pilot who said the company fired him illegally for declaring himself ...

Utah Local News - Salt Lake City News, Sports, Archive - The Salt Lake Tribune

first officer of SkyWest Airlines is suing the airline, claiming he was fired for whistleblowing about unsafe training practices


Pilot is suing, says SkyWest fired him for whistleblowing | Deseret News