Not sure how this escaped me before, but if we want to be sticklers about the propositions and proof, even if we interpret "God is justified in allowing evil" as "God is justified in allowing some evil" then Pater hasn't proven the proposition is necessarily true, only that it is possibly true, so I don't think I even need to concede that "God is justified in allowing some evil to exist". I'll concede the epistemic possibility of that, but tat is not the same as conceding that it is true.
However, and this is why I think my affirmative should actually be the central debate topic, one doesn't have to prove the necessity of God being justified in allowing evil in order to defeat my proposition. On a strict deductive form of the argument all one has to do is show that it is possible (but for all evil not just some), and that is why the strict deductive form is rarely used. In an evidential form it becomes necessary for the person trying to refute the proposition to show that is more plausible than not that God has justification for allowing evil, but not just some evil, but all evil.
I'm afraid our debate has become a bit of a schmozzle now because we didn't specify clearly enough some of these points before we started. I'd like to continue, and finish it up, but perhaps we might try again at a later date with an independent moderator who can help us set the terms more clearly before we start.