Hiding in plain sight has a lot of different meanings. Cryptography stands out a lot more than bickering among old men. Besides, which tools to trust? The PRC clearly distrusts many western crypto systems, why would AQ feel any differently?
Who cares if the CIA has a backdoor? It's still better to encrypt his archives than using plaintext. The chance the CIA might have a backdoor is lower than the chance the CIA might decipher plaintext.
Of course, you'd have to use a non-networked computer for this, in case Truecrypt phones home...
Well, the article didn't say that they were archived in plain text. For what we know, it may have been encrypted with TrueCrypt, and it may be readable by CIA.
If I remember correctly, there was at least one homemade cryptographic system they used in the past, but the US got a hold of it(and probably found a hole in it).
