I remember thinking that when I had the poster up as a kid. The reason is because the design sheets for the five 1984 characters have their chests facing to the left, whereas Inferno's faces to the right. Aesthetically, they needed another one to the right to make the poster balance. (Although Wheeljack's Universe pose would probably have looked all right [just not great], since his head and one foot are pointed to the right in that.)