Youssef, being Egyptian, knows Arabic...and likely has a firsthand knowlege of the expression. Steyn's is probably quoting a classic rendition of it. If anything, Steyn may be borrowing from Youssef--though likely they are saying the same things merely because they share the same worldview and opinion.
Yes. I just finished Steyn's book, and noticed a lot of parallels, not just that one. But an intelligent person could come up with many of them independently, or maybe they've both read some of the same sources.