I do not know, BUT i was thinking - I could be wrong

1) Maybe it is close to the current airport,
2) Maybe in case of a crash landing. A desert landing will kill almost all whereas a water landing will save a lot of lives. - Bechtel know what they are doing, i suppose.
3) Out of public way, the current airport flight path is over wakra and on the other side west bay hotels.

Just my thoughts, also, it maybe because of the scienic view.