I don’t think either PBS or NPR has been “bought” by anyone. They’re both still non-profits owned by their member stations.

Why would this make PBS and NPR sad?

It becomes useless as evidence unless you can establish authenticity. It just makes audio recordings more in a class with text documents; perfectly fakeable, but admissible with the right supporting information. So I agree it’s a change, but it’s not the end of audio evidence, and it’s a change in a direction which courts already have experience.