Bitcoin source code and the white paper were both published under the MIT license.

Perhaps the MIT license is not completely unrestricted?

It's interesting that there is a copyright on the Bitcoin Core source code, which is owned by "The Bitcoin Core developers". This means that the code cannot be used 100% without restriction, with the single case that  can be protected against being that if someone were to claim that they wrote the code instead of acknowledging the developers who did. Who knows -- the copyright owners might even be able to stop others from using their code entirely, if those others performed continual mis-acknowledgement?? Has that ever been tested?