This is the most extreme betrayal of trust we have witnessed so far, it's almost a statement against the people with anti-government sentiment forcing us to "face the reality", that we cannot do business that depends on mutual trust without the helping hand of the State.
If I were based in the UK, I would have already contacted a lawyer and/or the police to try to move the violent arm of the Law against him with full force. (*) There is a limit on how much one can scam, steal and cause general mayhem with impunity even in the BTCsphere.
(*) But I do not discard the idea of doing it from where I am. Maybe some of like-minded GLBSE users may start to cooperate to try to force him to clear his mess now or face some legal consequence.