"Creative Differences" will be the official line. Which I find strange considering he's very experienced and worked with Scott on Martian.
Yet it's the most logical reason.
Director's do a film every year when they're very active or every 2 - 4 years when it's longer project (or finding money is an issue).
While on the other side, actors, composer, assistant director, DP, editor, blablabla do sometimes more than 10 films a year to make a living.
