If they were smart they'd have flooded the room with sleeping gas. Metal bat gets stronger the more he fights, so using a method that stops him without fighting directly is the way to go.
I'm doubtful that he dies in one hit like that. Could be a shadow clone or he might just have some regeneration techniques. Either way I bet hes going to be weakened enough that he cant just crush anyone who messes with the MC but still powerful enough that he isnt a burden.