NVC in practice is quite useful for a boss to address behavior without escalation. In that case, its not important to enable discussion. Its important to get the job moving forward. And to find out if that's not going to happen, so alternatives can be selected (moving the person to a different task; providing resources so they can succeed; or even letting the person go).

Remember its a business with business goals. Not to be heartless but to earn pay, some performance is required.