It would help to know who was the previous Chief Design Officer.
It's possible they created a new 'C' position specifically to suit the role Ive plays and part of that includes a more flexible schedule.
It's equally as possible Ive didn't want a C-level position because internal red tape would keep him from being with the engineers and designers.
Really all kinds of explanations, but I want to know. It's really interesting to observe how large companies like Apple make personnel decisions.