That hand gesture means "stop" or "no" in Japan. Likely refers to "Fake Borger" in the context.
Indeed, there are many different meanings in other cultures. Fun fact, the Olympic Salute (similar to the Roman salute) was sometimes misidentified as the Nazi salute in the Olympic games in 1936, from that year on, it became less used to now being almost non-existant, due to the similarities they had. The similarities even extended to the 'Bellamy salute' which was used in America to salute to the flag, of course, many Americans began to distance themselves from this following the rise in the Nazi party and fascist rule in Italy at the time and eventually this style of saluting has become a faux-pas all across the west and sometimes even east.
