Well, Affleck did say that he would “absolutely not” direct for James Gunn’s DCU, and he also stated late last year that he would only direct movies from his production company from now on. Plus, Gunn has been radio silent about Affleck directing for the DCU since that interview. A bunch of people on Twitter accused him of lying, and he didn’t say a word in response, which is very unlike him.
To be perfectly blunt, it doesn’t seem like Affleck was ever interested. That leaves two possibilities; either Gunn misinterpreted the situation, or he wasn’t being honest.