I believe that the map in the first message of this thread is being mischaracterized. If you notice, the scale is labeled, "Combine weighted data, legal and taboo scores". Understandably, the first response asks, "What exactly is this measuring?". That question never gets answered and I couldn't find an answer myself.
The OP later posts a scale that actually goes to another map. That scale goes with this map:
As you will see, this map looks quite a bit different than the previous one. I still don't know what the first map is illustrating.