What's the legal basis for journalists' notes being "privileged"? There's protections for lawyers and doctors, but what exists for journalists aside from a vague sense of "journalism is important for democracy"?
"Reporters privilege"
It's also just common sense. If you make it easy for anyone to sue a journalist in a way that requires them to reveal their confidential sources, the sources are no longer confidential, and people in the future won't feel safe sharing information with journalists for fear of being exposed through bogus lawsuits.
It's in the category of "you better have a damn good probable cause" if you want to forcibly intervene with publishing.