I've tried to come up with a simple analogy to show my point how you cannot apply libertarianism to the island scenario and I've failed, but I did come up with thisL
Say we were arguing about golf swings. I say a high club head speed with lots of rotational action is the best swing and you say that is false, a slower club head speed with a steady upper body and more wrist action is the best golf swing.
To prove your point, you tell me to go back to the beginning of the game and ask me if I would use my swing. I have to admit I wouldn't, because with wooden shafts and feather balls, I would break the equipment. I would have to use your swing.
Would that prove that I was wrong? Would that prove anything? No, of course not. With the given situation as it is today, I am right. But this situation only evolved recently, so of course I couldn't apply it to a situation that happened before my theory evolved.
Taken even a step further, if I find myself on a desert island today with nothing to make golf clubs out of but rocks and wooden shafts, my swing would still be wrong. But that doesn't prove anything about my golf swing being wrong in the situation I am applying it to.
Yea, I know, not the clearest, but I hope you see my point. You can't try apply theories to situations they were never meant to be applied to.