Sodium is an essential electrolyte needed for muscle contractions. Too much sodium is not good but you don't want to eliminate it either. If you are following a typical bodybuilding diet and not eating processed foods, you will be getting very little sodium in your diet so you will need to add sodium to your diet through things like salted nuts.
However, there are much better options then peanuts. Peanuts are not a healthy food at all. They were so heavily marketed in the 1960s to keep the American peanut farmers in business. Peanuts are very fungus forming and have a very poor fatty acid profile. They have way too many omega 6 fatty acids and not near enough omega 3. Peanuts are also high in pyruvic acid which is an anti-nutrient in the body. It binds to minerals in your intestines and prevents them from being absorbed.
Almonds, walnuts, pistachios and brazil nuts are such better options. If you like salted peanuts, try salted almonds instead.