Overall, the UDR was moral. The Ulster Defence Regiment behaved ethically for the most part.
A tiny number of the UDR were in loyalist terrorist outfits. These men were sent to prison.
McGuinness was stopped by the UDR as he drove his car. McGuinness was a self confessed IRA leader. He was planning the murder of UDR soldiers. They were usually killed off duty and unarmed.
Despite all this the UDR were courteous and said please. McGuinness was not worried because he knew that the UDR would not harm him at all. They obeyed the law. His criminals did not.
Look at 3:25 on this video when McGuinness meet the UDR. Their courage is admirable.