In my state keys in the ignition engine running equals operation ...I have a friend who was in a ski town same situation ..he claims he was cold so had the engine running but
the court system had heard that claim many times before and was unimpressed

the problem here IMHO is the recency of the DUI...Was the case even adjudicated yet ?Did he recieve a sentence ?Was his license reinstated ? Need more info .Also how old is he ?