Okay, in terms of the way it's used in conjunction with demonology on the show, christian iconography is used frequently, thus the reference to christian uses of salt. in terms of the other uses of salt, they are aligned with more secular, i.e. non-church related, i.e. uses of it in relation to the supernatural (which is how it is used in the show). thus the references to non-church related 'magical' folklore surrounding salt in this piece. it wasn't intended to encompass the high cultural practices surrounding salt in every culture in the world.

I'm sure entire books could be written on the mystical uses of salt in global cultures. in fact, that'd be an awesome thing to do over at the salt page on super-wiki. (hint, hint)