It can be republished only provided no charge is made. They want a book that the author owns the rights to, and is willing to put out under CC-BY.
Just because something has a liberal licence, doesn't mean it's compatible with other liberal licences. This ebook, for example, would not be considered FOSS (it couldn't be put in Debian, for example).
Also, you realize it's from a California State edu address, right? It isn't just some random e-book.