I feel the literature is ambiguous on the matter. From the citation below I understand that HCV prevents auphagosomes' fusion with lysosomes, where the UPR fails to complete, i.e. HCV will exploit these not-destroyed EPR-elements for its needs. Whereas, we actually do not know what happens during fasting -- does fasting induce an effective destruction of the old-and-nonfunctional, induction of successful autophagy? -- (yes?) if yes, theoretically it should mess-up the plans of HCV ... And, yes, this is all in theory. I feel, given these many speculations, you are right in counselling Rainbow to beware of long fasts, since he does not have access to medical assistance. Although, if it was me, I would give them a shot, while checking liver often. Maybe soft fasting - juicing and fruits - is better for him, since I am positive having read stories of people with hepatitis C who had good outcomes with soft fasting. What is more worrisome, is the concept of eating-right, since many people think they have it right, but they actually don't; .. and since body building, which Rainbow is into, involves a lot of protein handling and recycling, which HCV might take advantage of.
"Autophagy removes long-lived proteins and damaged organelles and is important for maintaining cellular homeostasis. It can also serve in innate immunity to remove intracellular pathogens. As such, viruses have evolved different mechanisms to subvert this innate immune response. We have recently demonstrated that hepatitis C virus (HCV) can also suppress autophagic protein degradation by suppressing the fusion between autophagosomes and lysosomes. This suppression causes the accumulation of autophagosomes and enhances HCV RNA replication. Our further analysis indicated that the induction of autophagosomes by HCV is dependent on the unfolded protein response (UPR). Our studies thus delineate a molecular pathway by which HCV induces autophagosomes. The prolonged perturbation of the autophagic pathway by HCV likely plays an important role in HCV pathogenesis."