If the epistemic standard is a well-understood mechanism for HIV causing AIDS then yes I would say that hadn't been identified at the time, but the review I lin

If the epistemic standard is a well-understood mechanism for HIV causing AIDS then yes I would say that hadn't been identified at the time, but the review I linked admits as such. Moreover if what you disapprove of is the standard of evidence demonstrated by the medical community at the time then I think I can understand that even if I disagree with it. What I can't understand is why you think this is relevant to why Kary Mullis was a denialist, since it's clear he remained as such long after the evidence was overwhelming, the mechanism was demonstrated, etc.