Granted that the innocent should not be shot. I don't think you'll find anyone to take the other side of that argument. Nonetheless, the question of "proving" guilt does not even enter into the consideration when the police are initially encountering a suspect. At that point it is about restoring order (making sure everyone is safe) and beginning to gather evidence. The notion "proof" having relevance in the initial police encounter with a civilian is the portion of the comment I was reacting to.
