Representation by HR

[CD Power]

Is it illegal or unethical to advice a person(s) in a meeting with the company president or direct supervisor that they:
1. have 72 hours to decide if they will abide by their supervisors decisions or resign without representation from HR or any other individual;
2. say that termination will be immediate if that specific conversation is shared with anyone in the business or outside the business including Human Resource Coordinator

It is not strictly illegal but if your company has any employee manual or policy book they normally need to follow that and that certainly may not comply with the rules and procedures that you all agreed.

[Bricks41]

To be brief, a company would tend to always have someone from HR be involved during any counseling session.

Can you provide more information? What was the circumstances?

It sounds like they might be strong-arming you, but there is no way to tell unless you provide more information.