This is not only morally true; it's legally true. If Bain had committed bad acts during the period in question, Romney would undoubtedly be on the hook for it, regardless of whether he'd done the bad acts personally or even known about the bad acts. Whether you were paying attention or not would be and is irrelevant. And just as irrelevant if you'd delegated your responsibilities to someone else. Just doesn't matter. You're CEO, you're responsible. End of story.
(It's a separate and interesting question why an acting CEO was never appointed if Romney was off in another state for years working full-time doing something else.)
To say that you were CEO, owner, Chairman of the Board and all the rest and yet had no responsibility for anything that happened just amounts to elaborate buck-passing. And that's why this is a losing battle for Romney. Every technical argument about delegation, lack of knowledge and everything else just drives home the point.