The reason salt is inflammatory and why you might think it is bad for MS is simply because most of the salts that most people consume are basically "junk" salt. This is also very true of many of the sea salts that are on the market. Chemically these salts are sort of equivalent to what is used to make PVC plastic. This plastic is great for an underground irrigation system or a sewer pipe but not so good for your body. These salts are basically over processed and scrubbed of the many micronutrients that are necessary for the body to properly process. The problem is that when salt is studied from a dietary perspective, a distinction isn't made between good, healthy salts and over processed junk salts, which unfortunately most salts are.
True Himalayan or what is called "dirty" salt is loaded with micronutrients, which all combine to feed the body in an entirely different way, as nature has intended. This is why foods that come from the sea such as seaweed, sea vegetables, etc. are so healthy, becoming more important, and are being studied much more often. Comparing this kind of salt to the junk salts would be like comparing the nutritional value of farm raised fish that are fed junk food grain to that of natural fish that feed in the ocean.
There is quite a bit of good science out there about the benefits of real salt if you take the time to research it. It's really important to change the conversation and look at the chemical makeup of our foods and understand that there are night and day differences nutritionally between how foods are sourced and processed. That makes all the difference in the world.