Trying to following the reasoning here. I'm getting it until here, "You have to introduce a new ownership rule to implement any form of IP, one that takes property rights in already-owned scarce resources from the libertarian owner and transfers it to a third party, just like any other socialistic welfare redistribution scheme."
I don't get how a new IP ownership rule necessarily takes scarce, owned resources from anyone.
For example, when I finish a novel and go to sell it to a publisher, I sell it with the backing of copyright law and my publisher sells it with the backing of copyright law. I don't see how the use of copyright law (the new IP ownership rule) takes any scarce and/or owned resource from anyone else.
Am I misunderstanding the idea on which your argument seems to hing?