But films are not the product of any 1 artist. The director is one of the most important artists in a production, that is true. But the director is still one guy. Rami Malek is also an artist. So is the cinematographer, the editor, the grip, the best boy, etc. No director ever has made a movie himself, and no actor has ever been the entire movie. Some cogs in the wheel are more important than others, but a film is still the sum of hundreds/thousands of artists working toward 1 final product. So to answer this question, can I separate Singer's work as a filmmaker from his personal life? Yes because other artists worked on this film, also. It's not just him.
I've worked a variety of film jobs, and I have worked on films with people who did things that I only learned about later. Granted, I've never worked on a major production like X-Men or Bohemian Rhapsody, but still even on my much smaller scale, I would hate for my efforts on those films to be wasted because 1 dude on set was apparently a garbage person.