The problem is, it's not actually Doomsday himself, it's the virus. Could've worked if the user was infected, but they can just replicate the state Superman is in and count as already being infected without being infected.
Wouldn't the user just replicate and enhance the abilities Superman with the Doomsday Virus have? Because Superpower Replication just copies powers, Total Mimicry can copy states and such. But Superpower Replication can only mimic superpowers and that's it.
If they replicate the powers of Doomsday Virus, they cannot be infected because technically they already are, by skipping the infection stage, meaning it's impossible to be infected. As I'm guessing from this point on.