No, a property transfer has two parties
So you're a libertarian. You think property rights have some sort of objective platonic existence apart from the social framework they exist in. Fair enough, tone flag all you want, but it'd be nice if you adressed my arguments as well.
I gave examples that even people who run bitcoin tumblers, presumably even more hardcore libertarians than you, do in fact object to anonymising some people's payments (namely, the FBI's, or anyone taking money from them). Whereas they earlier had anonymized even known stolen money (from hacks, scams etc.) when the FBI is involved, they suddenly think some people don't have the right to anonymous payments. And we're not just talking the FBI here, we're talking any people getting money the FBI at one time touched - so they can't just say that government is especially evul so normal rules don't apply wrt. them.
People using zerocoin or coinjoin get privacy for their own information-leaking transactions - but at the cost of getting coin that may have been involved in some extremely evil shit. "Well, nobody would care about that since they know you got them blindly", advocates say. Not so. You risk people treating it like stolen goods and demanding its return, just like Jewish families demand the return of art stolen during WW2, or Egyptians demand back stuff from the British Museum.
So you got that stuff good faith? Tough luck, people don't have to be reasonable (and there's a question of how innocent you are, since you participated in a scheme capable of obfuscating even the most vile and illegitimate property transfers).
Property claims don't go away so easily. Much as you would like it, the block chain isn't the final word on who legitimately owns what.
For that matter, it doesn't have to be governments or nice and upstanding citizens demanding return of stolen goods. Picture this scenario: Someone burns a mafia boss for $100000 in bitcoin. He swears that he'll get his revenge on whoever holds the coin, and tells the world (in order that the thief should get as much trouble as possible cashing out, and pay as high a premium as possible). However, the thief uses zerocoin. So do you, because you thought it a little awkward to buy condoms. From Zerocoin you end up with a coin stolen from the mafia boss. Unfortunately, you never heard of the mafia boss' ultimatum, and you get gunned down some weeks after spending the money at a known location. A libertarian martyr, for the thief's inherent right to anonymously transfer stolen money. Worth it? I think not.
That's an extreme example. But it shows that the whole premise of tumblers, decentralized (like zerocoin) or not, is that people will give up their claims on an asset just because it's passed through many oblivious hands. That is a flawed premise. Only people who don't get that will be dumb enough to put clean money into tumblers.