To prevent this sort of thing happening in future why doesn't theymos cede control of the forum to someone he trusts who lives in Russia or Belize or wherever, and who is willing to ignore such subpoenas?
Because the last entity you want to piss off is the US Government. If you stick your fingers up at them they'll find a way to insert them into you. While we all agree that bitcointalk.org shouldn't have been subject to such sweeping requests for information, there is little reason to start a war over it.