It's a value judgement.
From the point of an officer in danger, a killed adversary is one where they can be 100% sure that the danger from that particular individual is eliminated. That's just good policy if your main objective is to save police officer's live above all.
If you're concerned that the general populace in general and the criminals with guns do not forfeit their chance at life for being in the wrong place at the wrong time or indeed be violent criminals out with guns to kill people, then that approach of "if you see a lethal threat, try to kill it", becomes less desirable, because innocent people get killed.
And while you are free to argue the difference of "shoot-too-soon" vs. "shoot-to-kill", the issue is, you might agree, that the outcome of shooting-too-soon-in-the-head and shooting-too-soon-in-the leg are decidedly different.
In the end arguing about whether the training someone to assess a situation before acting on it, is a little moot in general: Many of these situations involve incomplete information and the immediate need to act on it. In this case the officers say that, due to the guiding laser, they were under the impression to be in imminent danger. I sympathize with their lack of information to take easy decisions on.
But they point is: if they had decided to shoot to disable instead of kill, he would still be alive today, as would they be.
And even considering an actual armed adversary who was trying to take their lives, shooting to disable him would, often enough, still get them out of immediate danger to reassess how to apprehend the person and bring them to justice, instead of delivering a death sentence on the spot.
You might disagree, but a government policy which willingly accounts for the death of innocent people by direct force of the executive, to me, is fucking stupid.
You might argue that that's reverse, that a shoot-to-incapacitate policy would backfire, as officers would draw their guns more often perhaps, and I would agree. It's not the only thing wrong with policing today.