Too much salt is bad also, but we need salt, to survive. We were created in that way. Perhaps that was on purpose, for symbolical reasons planned already at that time, who knows. Have salt in yourselves, and have peace with one another. Well, perhaps through the covenant meaning.
Salt is used in making covenants - friendship .
For instance in Finland, when elder people who know the old customs go on their first visit at someone's new home, they take salt and bread as gifts to the ones who have moved into that new home. The beard of Aaron, Running down on the edge of his garments. Here we see brethren dwelling in unity. Oh, that precious oil in this psalm is that very special salted anointing oil which was mentioned earlier. The anointing oil for the priesthood.