[obblekk]

Places with the saltwater don't want to build large pipelines to send it to places without.

The places without are so dry they cannot drill, condense or truck in salt water, even though they have plenty of solar.

That's a coordination problem with public rights of way issues which is why it wouldn't happen without specific government policy.

[MostlyStable]

You realize that desal is already being used in various places in the world, including for (secondarily) ag, right? So there are already places producing the brine. Why aren't they mining it for value? As far as I'm aware, it is universally being discharged.

So either it's harder to extract value from it than this person supposes or no one else has ever thought to try and get value from it.

The second one isn't impossible but I'm not just going to believe it with no evidence.