A second, subtler use of the Worst Argument In The World goes like this: “X is in a category whose archetypal member is solely harmful. We immediately reject this archetypal X because it is solely harmful. Therefore, we should also immediately reject X, even though it in fact has some benefit which may outweigh the harm.”
Theft is however not solely harmful, obviously one party gains.
For most people I know, that is in the swedish libertarian community, theft is theft whether or not it has socially beneficial effects, because we use the definition that you gave; theft is taking from others without their consent. The implication is not that “As theft is always bad, it should be dismissed without a thought”, because some libertarians do favor theft and are explicit about it, because they believe it’s necessary. The moral breach of treating others as mere means to one’s own goals can be (hypothetically for most) mended if it has other good consequences (or such). The point is that taxation is bad, which doesn’t mean it should be dismissed out of hand, but it shouldn’t be adopted out of hand! That is, taxation should be considered a bad, until it is proven necessary or otherwise positive.
I want to defect, but so does the clip-maximizer. Since we both know that, and assuming that it is of equal intelligence than me, which will make it see through any of my attempt of an offer that would enable me to defect, I would try to find a way to give us the incentives to cooperate. That is—I don’t believe we will be able to reach solution (D,C), so let’s try for the next best thing, which is (C,C).
How about placing a bomb on two piles of substance S and giving the remote for the human pile to the clipmaximizer and the remote for its pile to the humans? In this scenario, if the clipmaximizer tries to take the humans’ pieces of S, they destroy its share, thus enabling it to only have a maximum of two S, which is what it already has. Thus it doesn’t want to try to defect, and the same for the humans.