I have yet to see a CEO actually take responsibility for anything. Its always some hand-wavey talk about strategy and unexpected decline in sales. Never once was it "I messed up."
I have, on the other hand, seen boards pile all the blame onto the C-Suite. Seems easy enough to pile the blame on an AI.
I haven't been directly involved with any large company CEOs, but the CEOs of smaller companies I have worked with have frequently been constantly dealing with responsibilities from many decisions they took (or didn't block). Some have personality traits that hide the pool of concerns beneath the surface. And a couple were genuinely taking the life in tourist mode (oblivious to any and all concerns beyond the very next steps).
The "AI CEO" problem is not fundamentally different from self driving car responsibility problems. You need a big entity to be on the hook (financially and legally) if you are really going for lowered responsibility on the decision machinery. I think it can work though (but with a LOT of effort), and that might be an interesting startup idea (we provide 90% of the CEO work via AI, you be in control of the remaining 10%, and responsible for maybe 20% of it; our "insurance" covers the other 80% of the responsibility).
I have, on the other hand, seen boards pile all the blame onto the C-Suite. Seems easy enough to pile the blame on an AI.