I read it differently. I read implied belief that Clemens used, I mean it's right there with B12 mockingly in quotes, but it is restrained by what he actually "knew". To me, the evolution of the Clemens saga only reinforces Canseco's credibility.
I've read there is a similar lack of hard evidence regarding ARod, so with his new book we won't know the truth. But, again, I'm not interested in pointing fingers. I just think it's unfair to classify anyone as stupid for thinking it when Jose is batting 1.000 on the subject.