We aren’t privy to the specifics of the legal paperwork James Gunn signed when coming aboard DC Studios. However, it makes sense it would prevent him from working with Marvel, given he’s the co-CEO and not just a writer-director working on a movie. He’s overseeing the entire slate of future DC movies, even announcing a full line-up for the first phase of the new DC Universe called “Gods and Monsters.”
Gunn occupies a different position than actors and directors, who are allowed to work with different studios. Essentially, he’s the Kevin Feige of DC, so all his attention should go toward ensuring this new cinematic universe is as successful as it can be. Understandably, the powers at be don’t want him getting distracted with other projects, and his overseeing numerous films and TV shows (directly writing several of them) is a good sign for DC’s future.
There was some level of crossover; Gunn received his position at DC Studios late in 2022, but he continued working on and promoting “Guardians of the Galaxy Vol. 3,” which came out in May 2023. More than likely, Gunn was allowed to complete his previously agreed-upon work, but from this point forward, it’s all DC all the time.
