Black Widow movie brings in new writer for rewrites.

Again, irrelevant. There's no law that says "When you hire a director, you also have to hire their spouse". There is no such thing as a "team package" when it comes to hiring for a job.

Feige could've just hired a female director to solely direct Captain Marvel (like Patty Jenkins did for Wonder Woman), but he didn't because he wanted a male director to direct the movie and only wanted a female "co-director" to parade in front of the cameras for media fluff.