The post argues that the Hayekian argument works a lot less well for prediction markets than it does for regular goods and services markets. You raise a good question as to how well it works even there. I don't have too much to say about that: I think its fair to say that the argument is something that most economists are vaguely aware of, but not something we spend a lot of time thinking about. For what it's worth, the idea always struck me as kind of sensible, but not as remotely justifying the radical free market conclusions that some people have wanted to draw from it.