If free speech only applies to government suppression of speech, then what would be the problem with a movie studio refusing to hire actors or directors who had

If free speech only applies to government suppression of speech, then what would be the problem with a movie studio refusing to hire actors or directors who had been involved in the Communist Party? Let's assume that the studio is outside CA so the following law does not apply: http://www.leginfo.ca.gov/cgi-bin/displaycode?section=lab&group=01001-02000&file=1101-1106 http://www.leginfo.ca.gov/cgi-bin/displaycode?section=lab&gr...