Actually, Stephen Halbrook is well known within the RKBA-defense community and has long been a champion of the right to keep and bear arms. My take on his letter is that he is going on the assumption that the [B]urn [A]ll {T]oddlers [F]irst crowd already have the names and addresses of all the buyers of the device.
He knows that the JBTs never really have felt terribly constrained by the Constitution and that the actions at Ruby Ridge and Waco have never seen justice done.
Whether someone wants to make a stand for their Second Amendment rights and fight it out like the Koreash crowd, or simply send in the device, is up to them. He is giving the advice which in their short-term best interest.
Then again, what this will mean in the long run is another matter. http://www.gunowners.org/op9805.htm