This being a rudder fix with minimal movement and tittle to no heat concerns, you would have to believe that grease would by far be preferable to salt water. Be it a stuffing box or a dripless bearing. The grease would not only provide lubrication to the stuffing material or bearing/seal, its high viscosity will act as a stop to the water. Is that not the reason modern flax products are saturated with teflon or whatever there using these days.
Agreed If there are other issues i.e. bad bushings or scored shaft it is not the cure all but even in those cases it could buy you time to fix it right.
Anyway,,, thank you all great conversation, I have learned a lot here.