Interesting read and sounds pretty close to my thinking on some of these "miracle" products...
Salt Away and the other so called salt solvent products are simply members of the car Wash and Shine family.
They all have a water wetter, which is usually a mild detergent. This helps wash away the salt by removing the surface tension of the water, and gives you some bubbles so as you can "see it working". Nothing new here, some of us have been flushing outboards with a detergent mixture for yonks, and you can bet it works, no question at all.
They also contain a silicon, which is suspended in the liquid and deposits onto the surfaces it alights on, under the water film. Because the silicon insulates the surface from oxygen, it tends to delay or even prevent oxidation for as long as the silicon film remains intact. It also dries to a shiney and streak free surface, and seemingly "repels" water, which beads up on the surface. I doubt the silicon builds up on itself, and similarly I would expect the next run to flush the stuff off the internal water cooling surfaces.
What you need to be careful of is the pH of the detergent, it needs to be neutral.(pH = 7.2) Some of these industrial wash products are slightly caustic, which is no problem on vehicle paint and chrome but possibly not good on ally hulls and engine blocks. For that reason alone I would always rinse off to get rid of the detergent, which itself can oxidise and become caustic.