I think the biggest argument against Voq being mind-swapped into a random Human body is that it makes having the same actor play both of them pretty pointless, especially since it's what gave away the whole game. What "if"? It happened at least twice in TOS with Darvin and Kirk going Romulan, and all the time in the TNG-era, at all levels of sophistication. Not just big-deal powers like the Federation, Romulans, and Cardassians, but even the random planet-of-the-week that planted the undercover agent Odo fell for into the Orion Syndicate could do it. If anything, all the saws and stuff in Ash's nightmare seem to show DSC's retcon is making it so changing your species from one brand of humanoid to another isn't as low-impact as getting a haircut.