Without figuring that part of the mystery out, the only solution would be for Maxmind to change the default location for the IP address for that zip code—but that would mean some other house would have strangers seeking smartphones knocking on their door.

There is an easy solution there. Change the "default location" for that zip-code to the lat/long of the nearest Police station. At least that way, the folks 'searching' for their lost phone can arrive at the right location to file a report of a lost/stolen phone.