8:45 The way i interpret it is that Killua feels if Gon defeats knuckle holding back, then goes to NGL, it will just get Gon killed because he isnt truly strong enough to fight the ants or stronger than knuckle if knuckle held back. Its hard to say for sure but thats my take on it. I dont think it Killua ever considered knuckle killing gon as a realistic outcome regardless.