Maybe This “cop” was taking off his gloves because he noticed all the other cops were NOT wearing gloves? JohnM posted photos of cops RIDING their motorcycles and they are NOT wearing gloves. Are ANY other officers wearing gloves?
Or he was wearing gloves so that his fellow conspirators could identify him as the fake cop who would direct traffic away so their flamboyant getaway car could get out of the traffic jam?
Above, this Bogus Motorcycle Cop is WEARING 1 GLOVE. We have no idea what happened to his missing glove. The object we see him holding in his (L) hand is rigid. That object maintains a consistent form/shape as he walks past Officer Harkness. A "glove" would Not do this. A glove would flop around with each step he takes. We do Not see this object doing that.
Also, when this Bogus Motorcycle Cop was previously filmed wearing 1 glove while walking along the string of passenger train cars, he was Not holding this object in his (L) hand. He produced the object we see in his (L) hand, AFTER the train car sequence on the Darnell Film. You mentioned, "...so that his fellow conspirators could identify him". I believe that the object we NOW see in his (L) hand, as he approaches the TSBD and the "getaway" Car, is going to do just that. The object he is holding in his (L) hand will ID him as a FRIENDLY to, ".........his fellow conspirators".