metrodriver: In fact I did address that angle above. If he was put into the car after advising the cop he was religiously prohibited from entering the car, he would not be Mechallel Shabbos by a goy putting him and taking him out of the car. He wouldn’t have to resist getting in or out, but advise the cop he was religiously prohibited from getting inside through his own volition and power.
Also, the cop would almost certainly not have arrested for refusing to sign. There haven’t been any jaywalking arrests in years, and his commander would have him in deep water if he brought a Jewish Sabbath observer to the precinct on his Sabbath because he was trying to observe his Sabbath — as the first jaywalking arrest in years. That would have gotten the police department in political hot water.