I don't think this does as much as people think
All of the photoso show him walking along deserted streets. So Google sees a slow moving batch of vehicles and interprets it as a traffic jam becuase it has no data to indicate otherwise.
If you tried to do this to cause a problem on a road that contains other traffic (either will a trolley full of phones, or by spoofed GPS readings, as some people were suggesting on Twatter), I imagine that the cars passing at normal speed would demonstrate to Google that there was no problem. If that wasn't the case, you would see roads marked as red each time a bus pulls in at a bus stop.