We don't have the full context, which probably includes a series of questions before this, and O'Donnell's increasing frustration that she was being asked about stuff that isn't really central to the book.
It should also be noted that the media treats the people it doesn't like contemptuously, such as when Piers Morgan here tells O'Donnell she's being "weird" about refusing to answer questions. With someone like Obama, Morgan would have changed the subject per request, rather than deciding this was now a Battle of Wills he had to win.
That said, I don't really get it. If there's a great deal more impertinence from Morgan before this (and I imagine there is some more), O'Donnell might appear more justified.
But... There really is no rule that hosts only ask about your current project. There never has been. They ask about that politely for a minute then talk about other things, because no one really wants to hear from most people plugging their new book.