The property should have been re-zoned to residential before selling it to this guy.

There were complaints, he must have a lot of traffic and cars coming and going to this place. He probably AirBNB's it to people for a big monthly haul. Or worse, has big parties there with cars parking all over the neighborhood, annoying all neighbors.

The real problem is he is using a residential place as a commercial place, and the neighbors are complaining. The property could be re-zoned to residential by the city, so why won't the city do that? And then they would limit his commercial activity in his residence, because it's affecting his neighborhood.