Most deserts are inhabited by endangered or threatened species. There aren't actually a lot of deserts so lifeless that you could avoid environmental activists getting in the way, at least not in the US.

US deserts are full of life; they're very far from lifeless. They're nothing like the endless sand dunes we envision when we think of the Sahara desert, Saudi Arabia, or the planet Arrakis.

The desert is far away. The ocean is much closer. Issues with increasing salinity go down drastically if you pump just a bit further into the ocean, where it is rapidly spread by currents. If that's considered too difficult/costly/energy demanding then pumping to a desert would be that much worse.

That kind of desert : https://en.m.wikipedia.org/wiki/Salar_de_Uyuni

Ed Staffords Into The Unknown visits salt harvesting sites in the Danakil Desert in Ethiopia in case somebody wants some more insights into this.

edit: Or here Aljazeera https://www.youtube.com/watch?v=PgDiW2ELx7k