If you want to be righteous and violent then their families are fair game, and then you'll get a lot of other opportunities to be a hero when they re-escalate in response.
If you want to actually reduce the violence and killing, of both the cops and innocents, then you need to show restraint and fight them within the system.
The system doesn't work. As this fellow has been telling you. Also, he tried to use the system. It chewed him up and spit him out, as it tends to do when it is challenged in any way. He's moved on to another methodology now. The system has only itself to blame.
Killing bad cops won't get rid of bad cops so only the good ones are left, it will just turn good cops borderline and borderline cops bad.
That's an assumption, one that goes counter to the ones this society is based upon. It has its corollary in "executing criminals and the consequent huge collateral damage to their families won't deter crime, it'll just turn others borderline and the borderline into criminals."
But in fact, what it does is breeds restraint and caution, which moves the borderline away from criminality, and keeps those who weren't even borderline well aware that living right is worth the candle. And when we execute the criminal, they stop committing crimes.
What you want to avoid doing is executing the innocent (or doing anything else to them, for that matter) because they and their families tend to get righteously pissed. Whereas the families of murderers and rapists also get hurt and pissed, but generally speaking, at the criminal, not the system. "YOU brought this on us!" "How could you!" and similar reactions.
Now, if the cops know that engaging in fuckery will get them targeted, and that everyone will suffer if they act like jackasses, not just them, and their families know that such fuckery will also likely get them targeted, the most likely result is that they will begin to actually do their jobs as they were intended to be done.
This is the way of war against something. You go after everything to do with the enemy that has besieged you. You take out the infrastructure, you blockade supplies, you drop on cities and you drop on industry and you drop on troops. You make the cost of being your enemy so high that no one wants to be your enemy. You do it until the other side cries "no more, no more" and convinces you they mean it. Then you occupy them and watch them for a while. In the interim, everyone else watches and goes "good grief, I don't want to be their enemy!"
This guy hasn't decided to play tit-for-tat. He's gone to war. And I'm not talking about modern, trained-to-fail warfare designed to use up munitions and equipment and keep the trough full for the military industrial complex; I'm talking about fuck-we're-facing-hitler-and-tojo all-out nuke-em burn-em where they stand war. And just like that war, the boys in blue started this one. He's already done far more damage to them than they can do to him; will he be able to do enough to make a difference in the sick, decayed culture of police officers? Remains to be seen. I rather think he may have already done so. Odds are good there's at least a spark of awareness already circulating among the police (and not just in LA) that when you step on people unjustly, they may bite back in a way the system can't insulate them from. The more so, now that a powerful example is being set.
It's revolution, writ small. Been a long time coming.