You betray your ignorance about firearms. You cannot shoot to immobilize. Every shot taken is practically and legally a shot intending to kill. Real life is not a hollywood movie.
Someone knowledgeable of the subject, which you imply I am not, would know that shooting someone in the middle of their body is the standard operating procedure (and is potentially less fatal, but yes legally still intended to kill) rather than taking an (essentially) headshot as this officer did.
Also notice I did not say what the officer did was "against policy" or illegal, I simply said I didn't feel it was justified (especially with where the shot hit). It's for the department and the courts to decide if the officer violated his duty.
Shooting a center of mass is not at all about being "less fatal" it is about it being the biggest target with the biggest chance of stopping your adversary.
Did I say it was? I believe I used the word "potentially" in the reply you are commenting to. The officer was shooting from ~6ft away and had a firm grip and was well composed, if they can't hit the chest of a target that was mostly still at the moment of the shot then they need to be spending a lot more time in the gun range (at the absolute minimum).
Not at all unlikely.