Out looking in, this probably would have made the most sense (still does), so there must be a really good reason why ES didn't choose this route.
Someone else was announced as a co-artist early this year, weren't they? Not sure what happened to that plan.
Perhaps Eric didn't want Nate to feel like the book was being yanked away from him, and as a gesture of support offered to leave the project open until he was ready to come back and finish it.
As that may be true, it's still a horrible business move....the book was so hot.