Bill Cosby’s testimony was supposed to be sealed as well.
There is a lesson here, somewhere, if you get accused of a crime and are promised a level of immunity in exchanged for your sealed testimony.
It’s an extension of the classic university lecture
Don’t Talk to the Police
https://youtu.be/d-7o9xYp7eE
The classic examples of that are Martha Stewart and Scooter Libby. You can now probably add Gen. Flynn.