He explains the difference between sharia and fiqh (Sharia is the will of God revealed in the Quran and in the life of Mohammed. Fiqh is the interpretation of God's will by scholars applying their reason), but he doesn't say anything about the question to which people attach the most importance nowadays, to wit: What, exactly, is the content of sharia? What is it that most Muslims - not the "radicals," but average devout Muslims who wish to live according to sharia - believe that the Quran teaches?
One thing I think we can say about sharia is that it's not what Westerners would call "moderate."
Suppose you found yourself among a group of people which, it eventually became clear to you:
- held approximately the same views about gays as the Westboro Baptists, only worse.
- held approximately the same views about women as Jim Crow era southerners held about blacks.
- held approximately the same views about Jews as did the Nazis.
- held approximately the same views about freedom of religion as medieval inquisitors.
- held approximately the same views about freedom of speech as the North Korean government
- held approximately the same views about human equality as advocates of the Hindu caste system.
One reason why it seems so easy to radicalize young Muslim men and turn them into murderous terrorists may well be that for a great many young Muslim men the ideological distance they must travel from mainstream beliefs to radicalization is not really all that far.