If the Casey's interest is in terraforming the American West to support substantial population growth, I would start with the Columbia River Basin and identify the bottlenecks to growth there.
The Columbia River drainage basin is larger than the Great Basin (670k km2 [1] vs 541 km2 [3]), it's the 4th largest river in the US by flow [1], and there are already existing megaprojects like the Columbia Basin Project [2] that have unmet potential.
If the growth Casey envisions isn't happening and/or won't happen with the easy access to substantial volumes fresh water of the Columbia River then it's very unlikely to occur in the scenario they envision with desal + pumping water into the Great Basin.
- [1] https://en.wikipedia.org/wiki/Columbia_River - [2] https://en.wikipedia.org/wiki/Columbia_Basin_Project - [3] https://en.wikipedia.org/wiki/Great_Basin