I have a competitor that ranks in Google Search for a Top Dollar Keyword in the organic rankings with the normal result, however just below that it shows another result that contains the Local City Name followed by their business name.
In the URL they have domain.com > Local
and below the description data it shows a map for a totally different location as this competitor only has one location...
Once clicking on the link I found that it has everything in the title, description and h1 and body content in footer that talks about the local area but not their product.
and when you click the breadcrumbs you can go back to a directory of all the other cities and states they are targeting with doorway pages with the same layout however the anchor text is cityname+keyword
Local listings always seem to have been a tricky one for Google, since they rely on "self reporting" which, at best, needs access to a physical address. I can remember a whole host of different local listing quality problems over the years. Sooner or later, Google will fix it up (or you could report it).
But essentially your competitor is exploiting bugs in the system, and until those bugs are fixed, I don't think there's a whole lot you can do about it. There is the "report a problem" button in maps too, though.
Thinking laterally, can you search for a directory that lists the competitor for all those locations? I am thinking if the creation of a lot of fake directories could create citations that are fooling Google.