A manager “accepting responsibility” for a major mistake is a flexible, almost meaningless concept in our modern society. In Japan, it used to mean hurling yourself off the roof of the nearest skyscraper (and before that, ritually eviscerating yourself); in other societies, it means—or meant—at a minimum, resigning your position. Nowadays, it just means uttering the words “I accept responsibility”, and little else, no real consequences.
McDermott “accepts responsibility” for those 13 seconds only in this latter, modern sense. Maybe that’s why people are not satisfied with his stance on this whole fiasco…