He was probably doing Arnold Schwarzenegger a favor to help him push the movie during the marketing campaign. This time around he is actually involved as producer and co-wrote the story for the movie. This project was set up by him and Tim Miller (and David Ellison) from the get-go. Charles Eglee is another collaborator of Cameron's, having worked with him on (yikes) "Piranha II" and TV's "Dark Angel."
I know that it's cool to bash Cameron nowadays, but let's have some faith in him... and Miller. Especially after "Love + Death + Robots" it should be clear that the latter has a knack for this kind of science fiction.