Colby, Are you capable of reading a dictionary? Why don't you try looking up the meaning of the word rivet. By definition a rivet is a piece of metal that is formed or peened over on BOTH ends. There are no threads on a rivet. If it has threads, it CANNOT by definition be a rivet. Here is what you need to do if you have the backbone and courage to learn some facts about Stars. Remove the nuts and bolts that hold the side frames together and also the axle nuts. Pull the drive hubs off the axle and you will see in all of their glory and majesty square threaded nuts that hold the spokes in place. Your problem is you are only looking at one end of the spoke and not the other end.
I know you have no intention of doing this because you truly are a lost cause and have no interest in learning something new.