Considering that his starting point is agnosticism compared to atheism as a belief in the nonexistence of god, the argument simply redefines atheism to win. It comes down to definitions. Atheism as 'belief in no god' -- that's not me, I'm not that atheist. Atheism as 'lack of belief in a god' -- that's me, I'm that atheist.

I see the two referred to as 'strong' and 'weak' atheism, and it doesn't help that I mix the two up myself -- overall I am 'weak,' but re: xianity I am 'strong.'