You misunderstand my position. I don't think that people's claims are evidence for anything.

When I invite people to imagine the zombie world, this is not because once they believe that they can do so, this belief (about their imaginative capabilities) is evidence for anything. Rather, it's the fact that the zombie world is coherently conceivable that is the evidence, and engaging in the appropriate act of imagination is simply a psychological precondition for grasping this evidence.

That's not to say that whenever you believe that you've coherently imagined X, you thereby have the fact that X is coherently conceivable amongst your evidence. For this may not be a fact at all.

(This probably won't make sense to anyone who doesn't know any epistemology. Basically I'm rejecting the dialectical or "neutral" view of evidence. Two participants in a debate may be unable to agree even about what the evidence is, because sometimes whether something qualifies as evidence or not will depend on which of the contending views is actually correct. Which is to reiterate that the disagreement between me and Lukeprog, say, is about epistemological principles, and not any empirical matter of fact.)