I don't know how Star Wars got into this, but the difference between this and wearing a Darth Vader shirt is that Vader isn't fucking real and he never actually killed or oppressed anyone. Hydra on the other hand is made up of fictionalized real-life Nazis who participated in World War II and want to bring fascism to a fictionalized version of America. It's a pretty big difference, especially in current times when real fascists control our government.