The author argues that if you decide that there is no such thing as free will, that that is a proof of you having free will. He does this with a long argument, possibly using a different definition of free will. I think that the longer you deliberately think about a decision, does not make that you have ('more of') a free will. Because thinking itself requires many small decisions. And all those decisions are not voluntary. I guess that not everyone has the mental capabilities to arrive at the conclusion of not having a free will and I get the impression that there are just a few people, or maybe no one, who can grasp what it means to not have a free will, I think, because the illusion of having a free will (and all the social constructs with respect to blame and guilt) is so strong that it is (very) hard to escape it (permantly).