Joe B.,
Thanks for the link.... hope you're having a good winter!!!
Now I might be in error, please someone in the know correct me if needed, but the first diagram in the .pdf is that of the original proposal for the BD Resort. To my knowledge, the area at the north end of the property that shows both an 18 and 9-hole course is the area that is covered by the entire Old Mac routing.
Also, IMO I would not worry too much about the 600 houses. As with many master plans that are attached to long-term projects, plans can/do change sometimes significantly. Do I believe there will a housing component to the property? YES, but nowhere near that number.
As for the amount of play it will get.... I agree with Tim Book. I have worked for many guests that either do not want to or physically cannot walk 36 holes. Having the 12-hole par 3 will provide guests with another option. Also, at some times throughout the year when it is busy with shorter days, very few groups will have the chance to play 36.