So maybe they could try to solve it amicably and he does something to help that neighbor improve his property in some other fashion and they call it square?
Naw, it is every man for himself. No caring allowed, only whining, calling in the Big Nanny Of Vengeance.
As a professional who has years of construction arbitration and mediation experience, I will agree your suggestion sometimes leads to resolution.
Here, however, it appears other neighbors were damaged as well. Such a public nuisance with additional players does not always lend itself to a resolution which allows the nuisance to continue.
Nonetheless, I addressed only one of the issues: the blatant violation of the zoning statute. That issue could have arisen without neighbor input simply with an inspector that happened to drive by the house.
The owner appears to have committed two offenses, he not only violated zoning restrictions established for the benefit of the community, but also failed to get a building permit.
Not a good way to launch a request of local authorities for a zoning variance. Even worse, if he thumbed his nose at the judge by refusing to remove the structure from the sideset, he shouldn't be surprised to find himself sitting in the slammer.