To me, this smells quite a lot like a NSL (National Security Letter) or similar.
Perhaps even an order to put a back door into TrueCrypt.
To quote one commenter at Techdirt:
It’s gotta be either a compromised key or a hidden message. The development team wouldn’t in their right minds advise people to move from TrueCrypt to Bitlocker–that’s clearly ludicrous. The fact that they haven’t made any clarifications to their statement is equally telling, and it’s pretty easy to do the math. My guess is that they are under a gag order