Mouse, you're normally spot on but I am sorry - you're wrong on this one! Transparency is a HUGE problem in some countries. There's a world of difference between 'mishearing' something as its typed up with the minister for transport breathing down your neck in a small room, and being able to doctor a CVR tape to a point of non detectability (almost impossible without facilities and without someone finding out). Its the same reason there is a row between Kenya and Cameroun over the KQ 507 DFDR. They know what can happen. I agree, its about as likely as Russian secret agents poisoning dissidents with radioactive .... oh, that really did happen, didn't it?
Releasing CVR tapes onto the internet is unsavoury but aids transparency.