Well it can’t actually the play will need to be stopped. How are you going to get the player off the field without stopping it? Just some really poorly thought out knee jerk reactionsNo grand finals have been decided through dirty thuggery? Are you SURE?
As has already been explained, clearly a 3rd umpire doesn't need to stop play to investigate an incident. Play can continue for 1-2 minutes while the umpire watches the reply and makes a decision then the on-field umpire relays that at the next stoppage.