He was a mainstream Hollywood director, working with the biggest stars of the day, and co-founded the studio United Artists with Charlie Chaplin, Mary Pickford, and Douglas Fairbanks. The film was some controversial, but much less than you would hope. Most of the controversy is retrospective.
IMO, not a good choice by the writer to not make clear (especially to non americans) how incredibly racist the film was, even being released at the most racist time since slavery, and instead say it about the director.
https://static01.nyt.com/images/2016/02/05/arts/05FRIDAYFILE...