Political affiliation is not protected. Speech is not protected.
Stop whining about some made up "cancel culture." Unless you're a socialist. And if so, just admit it.
That film company can legally fire employees for being a Q-a-nut, or Magatarded, or racist, or ignorant, etc. Many other employers can do the same.
That's capitalism at work.
Actually unless you apply your corporate standards equally to all employees then firing one employee for an infraction but not another for the same infraction will get you into legal and EEOC trouble. This is clearly backed by a large number of court & EEOC decisions. Equal treatment is required in the workplace. If you don’t want to believe me then go discuss the topic with an employment lawyer.