If only those who were already slapped once in this manga wouldnt have to come back not only once but thrice to get slapped again. Also the author never makes them "remember" that the one who humiliated and beat them at some earlier point was the MC
nah. This is what the MC wanted his father to witness. He was telling him that those two were not who they pretended to be. Now, the father knows. The MC is gonna cripple the guy cuz he humiliated his father LOL