Is it possible that this is the result of a "dead man's switch" (DMS) set by the developer(s)? Perhaps a (continually updated) process was set up so that TrueCrypt would shut itself down if the developer were unable to prove he or she was still actively maintaining the software.
I can see a couple of scenarios where this would be wise:
A) The developer passes away, leaving nobody else to maintain TrueCrypt. Zero-day 1234 is discovered which compromises TrueCrypt. The DMS activates, depreciating the software and advising users to migrate to another alternative (why BitLocker, I have no idea).
B) The developer(s) is(are) coerced into compromising TrueCrypt in some way. As a part of the coercion, the developer(s) is(are) unable to demonstrate proof of life to the DMS, so the system nukes itself.
I can see a couple of scenarios where this would be wise:
A) The developer passes away, leaving nobody else to maintain TrueCrypt. Zero-day 1234 is discovered which compromises TrueCrypt. The DMS activates, depreciating the software and advising users to migrate to another alternative (why BitLocker, I have no idea).
B) The developer(s) is(are) coerced into compromising TrueCrypt in some way. As a part of the coercion, the developer(s) is(are) unable to demonstrate proof of life to the DMS, so the system nukes itself.