So it sounds like you are saying, in either instance (attorney/client, or not) that it should have been reported. It was about a crime (solicitation for murder), it was about a potential future crime, and one that would result in death. So attorney/client privilege wouldn’t be there to stop them from reporting it. And, as a/any responsible citizen, it should have been reported, even if the employee wasn’t a client....
No. I'm not saying that. First of all, an attorney doesn't have an ethical duty to report a plan to commit a crime that will result in death or great bodily injury. However, doing so is an exception to the ethical rules of confidentiality should they choose to do so.
Second, if they were breaching confidentiality to report a planned crime, they would need specifics.
Third, nothing suggests they were in a privileged relationship with the employee. So none of this applies. Then it just comes down to their personal feelings as to whether they should call someone about something an employee said, that another person supposedly said to the employee, about something that someone else supposedly said to another person.