Is there a case where the registrar was based outside the United States and the .com was shut down by the US Government? The best example to the contrary is thepiratebay.org where the PIR registry is based in the United States but the registrar is not. GLBSE.com is not registered by a US based registrar.
I must admit this is sad that the Internet is not decentralized enough to prevent such moves. TLD .com is managed by Verisign which is based in US, therefore it would be prudent to move GLBSE onto a different TLD, with a registrar and the TLD registry based in some liberal place.