I'm wondering what the legal ramifications might be if you set a secondary key that would wipe the drive in the most secure method possible and then provide that key. Or even the alternate boot sequence as suggested.
Destruction of evidence. http://en.wikipedia.org/wiki/Spoliation_of_evidence
I have to say that I somewhat agree with the ruling because there are similar situations with physical objects, not true one-to-one but they are there. I'm just wondering how the courts would react to the destruction of digital evidence that was not directly initiated by the defendant, but indirectly by preparing for the possibility.
There would be copies made and the drive that has the encrypted volume would likely be accessed with a "Write Blocker" forensic device, or in a virtual environment, etc.
This technique would only tip your hand that the volume contents changed after entering the password.