Validation on manager or employee

Summary:

How can we validate that the action is performed by an employee or a manager?

Content (required):

We'd like to put in place a validation for a termination that a manager can only terminate for a contingent worker. I would like to put in place a restriction that the manager gets an error message when wanting to terminate an employee but he should be able to resign himself as an employee. My current rule also throws an error message when the manager is resigning himself as he is an employee.

Please find attached the rule I've written. The use case is still under review (#9 - COE00563) but I'd like to already launch the question.