He said it was for a book that wasn't announced yet? So it's new and he's not just filling in on Son of Kal-El? And I check on his twitter and IG and he's got more and more Jon stuff that seems to also be from this project, so it looks like it's heavy on him.
My guess is that this might be a Jon lead Stormwatch book.
And I don't know if anyone at DC picked up on it, but having a Superman who is in part all about saving the environment lead a team called Stormwatch is high key dope.