That's not to say that a CS graduate is or isn't the ideal candidate for the program (I think he felt that they were). But securing systems and organizations is primarily not a technical problem. You should understand that and understand the reasons why.
Sure, but the best security programs don't even exist in the same department as CS.
At CMU Information Security is run by the College of Engineering, not by the CS department.
At NYU Cybersecurity is run by Tandon school of Engineering, not by the CS department.
At RIT Computing Security is run by ... the Department of Computing Security.
At JHU Cybersecurity is run by Whiting School of Engineering, not by the CS department.
This is because computer science and computer security are two entirely different disciplines.
The vast majority of the people who invented, built, and maintain all the systems infosec people are deploying had CS or CE degrees. A good CS degree provides an excellent foundation for infosec careers. In fact, at many institutions, the infosec major is very similar to the CS major.
It's not everything you need, which is why a CISO should minimally also spend some time as an individual contributor in an infosec or closely adjacent group.
You're moving the goalposts because your position that CISOs need no education whatsoever in the work they are leading is prime facie absurd.