Who holds the ceo responsible? The board. If the board themselves would have made the same hiring calls, it's unlikely they could fault the ceo for making those calls as well.

By extension -- who doesn't hold the ceo responsible? The court of public opinion, which is what all of these comments and articles spilling barrels of ink on this issue think should be the case, but is not actually the case (and for obviously good reasons). A company is not a democracy (again, for obviously good reasons).