The code was not open-sourced. It was only given to one party, and presumably did not come with a license to redistribute the source code. This means all users

The code was not open-sourced. It was only given to one party, and presumably did not come with a license to redistribute the source code. This means all users of the software are less safe. If the NSA can find a bug in the code, they can unlock everyone's files, but nobody else could ever uncover that bug.