In that case, my arguments against you seem to stand.
Excuse me, but I did figure that your definition of “exploitation” is your “exploitation criterion”. I’ve been pointing out how it doesn’t lead to the conclusions that you claim it leads to. How can you possibly not have seen it…? 
You’ve already implicitly conceded that time is not subjective (given your failure to respond to that part of my last post to you). Hence you also implicitly conceded that there is a temporal difference between initiation of violence and retaliation. If you are not defining “aggression” as I am, namely “the initiation of violence or the threat of violence”, then do tell, what definition are you using for “aggression”? Otherwise, I can’t make sense of the first part of your “criterion”, namely “If A hires C to use action on B that B used on A (in this case, aggression or threat thereof)”, because to me, retaliation (what A is hiring C to do) does not constitute aggression.
Now if your “criterion” is truly an analytic statement, then it is a premise, and as such it can not be proven nor disproven, only accepted or rejected. So why should any of the rest of us accept it?
I don’t think it’s an analytic statement, though, because if it were, then given your apparent definition for “exploitation”, the proposition “C is exploiting A” can only mean “C is using means on behalf of A that were done against A by B against B”. There can be no further meaning gleaned from that statement, based purely on the definition you’ve presented. So it almost seems as though you’re relying (or, at least, banking) on the rest of us to equivocate between the definition you’ve put forth and the definition we’re used to using. In that case, what you’re doing here is really just a sophisticated attempt at trolling.
You would do better, in fact, to simply claim that those who are best at wielding defensive violence would also be the best at aggressive violence. Your “exploitation criterion” is irrelevant. We can then go into the reasons why aggressive violence is not preferred over defensive violence by those who are the best at using violence. From what I can tell, your claim is that this is an illusion; following Hobbes, you’re arguing that, in fact, aggressive violence is overwhelmingly preferred over defensive violence. The reason why it seems otherwise, you say, is because most people have been prevented from wielding aggressive violence.
Empirically speaking, however, that does not seem to be the case (as I’ve already talked about before). Additionally, it seems difficult (if not impossible) to measure in absolute terms who is “better”, let alone “best”, at using violence. Somehow I think you already realize these things, hence your attempt to mask your underlying argument with your “exploitation criterion”.
First off, by what measure(s) of “strength” do you purport that one guy on the island is “stronger” than the other? My point here is that, as I mentioned in mgmcintyre’s question thread, the concept of “strength” is very context-dependent. Suffice it to say that brute force does not always win the day.
I also fail to see how either guy on the island has a territorial monopoly over anything on the island. “Assuming that the small guy has no chance of beating him” is quite an assumption to make – one that I categorically refuse to make myself.
Regardless of what Rothbard may or may not have meant, I’d say that things such as “who is the strongest in the area” are always in dispute. Look at sports, for example. Even after a particular football team wins the Super Bowl for a particular year, some people will dispute that another team was, in fact, the better or “stronger” team. Nothing of that sort is ever finally settled.