You are saying: "That was not the solution. But I don't know what the right solution is".
How can you possibly know that there is an alternative without knowing what it is?
I think what you are really saying is: "I have an ideological opposition to violence-as-a-tool which I cannot rationally explain". Or, "the consequences of violence-as-a-tool are so unthinkable that I choose to stop thinking."
Your line of thinking is responsible for the fact that this guy wasn't dealt with sooner. Maybe you should visit some of the victims of his behaviour before dismissing the seemingly-helpful vigilante justice in this situation.
The black-and-white line you're drawing between "blind justice" and "angry, vengeful townspeople" is not so clear in reality. Do we have AI algorithms for implementing first-principles justice? Are you so sure that first-principles justice doesn't include strategies which look like retaliation and revenge?
> "the consequences of violence-as-a-tool are so unthinkable that I choose to stop thinking."
And instead be something along the lines of.
Admitting exceptions where we allow violence-as-a-tool is more harmful than the harm prevented by violence here. Simply because the consequences of an exception set a precedent that lasts for a long time.
This does involve condemning people to their fate. Alternatively, you can take the position that sometimes people really should take an action they should simultaneously be condemned for.
If your actions are causing others to suffer, and you're willingly doing nothing to prevent that, and you have expended the patience of those around you, then you get what's coming. Maybe he shouldn't have been such a shithead.
Fortunately not many people seem to feel this way, maybe because revenge doesn't work as a criminal defense.
People who have been wronged are usually highly emotional and it's hard for them to put themselves outside of their circumstances and view the incident objectively.
Justice is supposed to be blind for good reason. If we all carried out our own version of justice, I'm sure you'd eventually run into someone who thought being too loud at night should be punishable by death.
There are many instances where victims of bullying feel they have no recourse other than revenge. I don't know the answer for how to make that situation better, but I know it's not murder.