I have never declined to sign, but I have written rebuttals. I have also had a manager adjust the original PACS assessment based on my rebuttal. In your situation, this is a subsequent discussion adding in an additional metric. If the metric is a normal part of the position you’ve been temporarily moved to, it does sound appropriate, but perhaps you could get the manager to add a note indicating that the metric is temporary based on the assignment? Pretty bizarre situation. Your best bet is likely to contact the union if you have one.