Turning McComiskey's argument against him

In "Disassembling Plato's Critique of Rhetoric in the Gorgias," McComiskey argues that, given his relativistic epistemology, there's no way Gorgias would have agreed to premises offered by Socrates that assume rationality, absolute truth, and a foundational epistemology. What McComiskey must argue, then, is that Plato knowingly altered the actual argument between Socrates and Gorgias for political reasons, and he offers a hypothesis about why Plato would have done this. But couldn't one take the same formal argument that McComiskey uses (namely, that given figure x's views, y, there would be no way that figure x would have uttered any speech that entails not y) and use it to refute McComiskey's entire thesis. In other words, isn't it just as plausible to argue that, given Plato's foundational epistemology, which entails an insistence on one, correct version of the truth, there's no way he could have altered what he knew to be a true account of the dialogue to produce a misleading account? The problem with McComiskey's argument is that if one finds it logical, one also has to accept the above refutation of it, which is equally as logical.