If I understand correctly, for speed of deployment they're building a less-efficient simple-cycle plant (instead of the typical combined-cycle). Even though it's larger, the efficiency is worse than a typical natural gas plant.

Natural gas is basically a waste product that gets flared off in many oil-producing parts of Texas. If this private power plant can use that gas for something productive then I guess at least we're no worse off. But it's not clear that is what is happening.