Sure, he should have made an unban application right away. He also needs the Screenshot to get the unban panel to consider his app.
But, that ship has sailed. So what now?
If he is clean, then it would be crazy not to unban him due to bureaucratic reasons. If we have the demos, we should look at them, then decide.
And to be honest.. he may change his name every 5 mins if he wants to. He might get banned 30% more often, but thats his risk. This is an admin mistake, not the players mistake. It might actually be a good thing, keeps the admins sharp & trained

greetz,
Legion