Actually I think all people...which includes any business...have the right to associate as they wish. So yes, on one hand its great she can be fired for this.
OTOH it goes both ways. I find out you are a BLM lover I should have no problem firing you. 4th Amendment.
Ive long said this discrimination law stuff needs to stop. 4th Amendment.
"Should." Do you really believe that's how it works?