Any kind of algorithmic classifier will have false positives for a given level of confidence. The lower the threshold at which you start banning sites the more false positives you will have, there is no silver bullet here.

So when Google decided to crack down on a class of sites sites that share enough traits with the sites that were being axed came into the danger zone and a number of those ended up being penalized enough that they are no longer viable / interesting enough to maintain.

This appears to be one of those cases.

Being dependent on a single entity your hosting, for the traffic you are receiving as well as the service you are directly promoting (in this case maps) makes you an add-on to their eco-system.

I wonder how many small but viable websites are still in this position and how many of them will give up after finding their traffic decimated because they ended up being a false positive in some filter.

It might be more productive to try to figure out what exactly caused the penalty, but I fully understand if the owner of the site just wants to move on and become as independent of this as he can.

Let's hope that 'pointing go google maps' versus 'pointing to open streetmaps' won't trigger another penalty because then he might lose what is still there or a good sized fraction of that.