What part of at-will do you not understand?This is not about political affiliation. It is about applying the same policies equally to all of their employees.
In this case they applied a workplace policy to one employee who was a female and did not apply the policy to a male. This is irrespective of the political affiliation or views for the employees. The actions are discriminatory.
In a normal workplace situation this would be a clear situation leading to EEOC action and the risk of the terminated employee suing.
Of course, in this particular situation we are talking about a star in Hollywood. Most likely Gina Carano has a contract for the Mandalorian. Likely there is a payout when the contract was terminated. Most likely lawyers on both sides are involved in determining the payout size and it comes with a written agreement from her not to sue -- plus other clauses to not badmouth LucasFilm, etc.
Furthermore. Prove that a male employee said the same exact thing that she said, but was treated differently.
Admit it. You're a socialist.