The AI move now but only after I fixed a bug with the movement code. I have discovered that I am spending a large amount of my time tweaking the movement code. Below demonstrates the difference in the code.
Notice how now the blue tiles representing an impassable river as well as other units now block the movement of characters, yet the red tiles represent the unit can attack the tile. This effectively was important to implement because it gives strategic options like blocking off choke points to force favorable fights.
I think it's time to finally make the game look presentable now that the hard technical stuff is figured out. I am quite pleased with the movement code now.