Though that Lightspeed hero and Rimuru ought to have absolutely no reason to fight each other, but it's nevertheless interesting the author still found a way out, despite making Rimuru so powerful nothing should be threatening him. When the hero has a reverse causality cheat skill, providing always the best outcome for him, it doesn't really matter how powerful his opponent is. Logically the cheap skill should ensure they won't fight, in this case, because neither has any reason nor desire to fight the other.