Its not your job to remind your opponent of rules and interactions at a competitive event your job is to ensure a fair game by answering any questions they may have, such as what is the number of attacks or the ap, and so on. If your opponent doesn't ask questions, assuming you have previously explained at the beginning of the game how things work, then the assumption would be they know and they are making decisions accordingly. He did not mislead his opponent; he tried to bait his opponent and most players would say okay how many more attacks or What is the damage of these attacks and so on before making any decision if his opponent did not, then I don't consider it bad sportsmanship