An LEO is in a similar position to me except they can use more pain compliance. We'd be very hard pressed to justify a KO. I wouldn't do it. Kyusho (pressure points) can be used for grappling and to enhance tuite also. In an early video of George Dillman made for law enforcement officers, he suggests the use of the arm bar which a triple warmer meridian maneuver, to assist with the handcuffing. In addition to controlling one arm, the cross extensor reflex action makes the subject bring the other arm back where you can reach it for the other ring of the cuff.
I'm not saying I would never uses St 9. I have. I'm just very careful with it. I'm more inclined to use it for control than KO. I accidentally KO'd (stage 1 with side effects) my coach with it a couple of weeks ago. He entered with a straight in punch. I blocked to the outside with cross palm block with the outside hand, and cover with the inside hand. That drew him in. Then I held my bent inside arm up with the elbow bent. No strike, no force... this was practice. In a real encounter, there would have been an intentional bicept strike to the throat. He walked right into the bend of my elbow striking both St 9 and his airway. Both legs buckled. He couldn't fight. His hands were shaking very badly. He sat down and was spilling his coffee all over the floor. Had it been a real fight, and not practice, I would have had my opportunity to finish him off.
I like St 9 for control. Let us say I had to pull a person off of another person from behind, with combatants standing or down on the floor. I could grab the SCM muscle by St 9 with the fingers and SI 16 with the thumbs. I've never actually tried that other than in practice, but in practice it is pretty compelling. It is probably as good as grabbing the hair and sets you up for a good follow-up better than grabbing the clothing. I think I posted on this earlier in this thread. Someone else tried it and they thought it was pretty good too.
Read the thread through from the beginning.
The older I get, the better I was!