It's a fair question you raise. In many of these situations, what's clear or not afterwards, may not have been clear at the moment. The big thing is not letting someone get their hands on you or getting into a scuffle situation, because then your primary job becomes protecting your pistol or weapon and not getting it taken or used against you by the suspect. Whatever you have left after that goes towards actually fighting the suspect. So the key is keeping the suspect out of arms reach of you. And that's part and parcel from the suspect injuring/killing you from letting them get too close while they're still a threat or otherwise not subdued.
One thing to remember is that a police officer is not responsible for the choices someone makes. That said, you try to minimize force if at all possible, but it's not always easy to fully anticipate the actions or intent of someone; and with the key being to protect yourself first, you may have to resort to deadly force quickly, especially when met with potential deadly force. Baton or spray are generally for unarmed non-compliant person. However, that too depends, with the totality of circumstances.....such as a large muscular person who has the potential to kill you easily and is making attempts to, such as my BP agent example. It's a tough call at the heat of the moment, and no one wants to end up in a flag-draped coffin due to choices someone else made or the problems that were theirs, that they made yours.
