While there might be a reason to make the distinction between the reasoning going on in Roko's argument and the reasoning going on in Roko's head, I have no access to the latter and so must evaluate the former.

Even if you had access to the latter, that has no bearing on your evaluation of the former. It's the explicit claims that we're looking at, the ones that are actually communicated, not what the person meant inside their head or what we think they might mean.