Because Moonbeam's buddies could buy 1000's of acres of worthless desert for pennies and then sell it back for a nice little profit[1].
[1] https://www.fresnobee.com/news/local/article218398575.html
[1] https://www.fresnobee.com/news/local/article218398575.html
IIRC, the valley-first alignment was part of the application for federal funds made when Arnold Schwarzenegger was governor, so it's unlikely it was motivated by concern for friends of the (at the time) once-and-future Governor Brown.
https://www.nytimes.com/2010/03/07/weekinreview/07mckinley.h...
[0] https://www.nytimes.com/2010/03/07/weekinreview/07mckinley.h...