The problem is not that the router is currently broadcasting a BSSID that exists elsewhere. The problem is that a geo-wifi database contains an association between their address and a BSSID.

They can change the router, and eventually the problem should sort itself out (if it is indeed their router and not a neighbor's that is the issue), but it's going to take until the old record ages out of the database for it to happen. And that could be months or years.