Did they record it for posterity? The pictures my parents took of me in the bathtub as a 2 year old are not something that should ever be public, even though in theory they will fall to public domain in a few years.

In the 1920s Harvard took naked pictures of all their students for research purposes - again things that should never be public. (this was an branch reading someone's personality/fortune from the bumps on their skull - at the time the idea was taken seriously) The pictures are available to serious researchers, but you have to go through great hoops to prove you are serious.

We do not know what is on those recordings. There might be some things where it is as obvious as the above why those who did the recording may not want anyone to know they did it.