Based on what I've observed of Dawkins, I doubt that his intentions are to fortify a defense. I think he's probably trying to create a rallying point for atheists.
82% of Americans believe in God. Source
83% of Americans are scientifically illiterate. Source
I don't believe that's a coincidence. If more people were educated about the facts and viewed religion objectively, I think there'd be a lot more empty churches. Dawkins knows this too, but acknowledges that atheists (being "independent, free-thinkers" in his words) are difficult to organize. I think this is his attempt to turn that around.