Didn't this all start by the employee in this case tweet in a public forum to his boss? So doesn't that mean the conversation is public by defintion?
Nearly everything Elon disclosed didn't need to be disclosed publicly.
Just because someone asks you a question publicly, it doesn't give you carte blanche to unload every single detail you know about the person asking the question.
There is not one single thing case in there that makes it OK for an employer to disclose medical information about you, however vague or detailed.