"unlike Islamic scholars, a true 'scholar' studies more than one book"

This joke by Dawkins somewhat annoyed me. Quick search in Google or Wikipedia would disprove this and make it a silly joke, so why make it in the first place? Don't Atheists, secularists and supporters of free speech know this bit about Islam? Perhaps the whole point is to 'offend' those who we disagree with? Anyone with answers?

Some jokes seek to contrast literal truth with a deeper obvious falseness, while others seek to contrast obvious literal falseness with a deeper truth. That joke is intended, I think, to be of the second kind: obvious literal falseness contrasting with a deeper truth.

That said, from what I know of Dawkins, he tends to be quite abrasive. He sometimes manages to get even atheists mad at him.