video; I'm sorry for the TL;DR
Right, so someone who murders to protect would be deemed better than someone who murders because they simply have the power to do so. Though, it's the one who holds the power that seems 'good' since he's a lawkeeper. There's also the chance that he can lessen the weight of his crime using his position.
But wouldn't you deem the criminal who murders to protect a better person than the lawkeeper who murders so their city's taxes are paid? Yet, according to most laws, that one criminal who is protecting others will likely be the one to be punished even though he is deemed a good person by others. It's a glitch in our law system since we place a person's rank and class above their actions and motivations. Perhaps Acumen's system could be the same.
Yet, the criminal who murders to protect is well aware of their choices, knowing there's a chance they could end up in prison for their crimes, yet it was a chance they were willing to make.
What I'm saying is that yes, you are correct that there are still criminals that will walk free in our worlds, however that doesn't mean we can avoid such punishment ourselves if we've also committed such crimes.