Here it's worth remembering that CISO is a "specific" role; it does not necessarily connote "most senior security person in the company"; some companies have more than one; some companies have a "CSO" and/or a chief of "risk"; at Apple (for all I know) it might just mean "most senior security person in IS&T". Apple has a sprawling and multifunctional security team.

If your claim is that all of security at Apple somehow reports up through IS&T, I have some reason to believe that is not the case.