Salt zombies

"Ye cannot abide salt, water, oil, the cross: and no marvel: no more cannot the devil, who possesseth you and rideth you." :^)

An aversion to salt is an old element of folklore, that gave this stuff the power to repel evil spirits, witches, and all manner of devils. Perhaps during his time on salt, the stuff of his body was infused with some of the dark energies of that plane, and his phobia of salt is the repulsion his now-living body feels as it tries to reject the foreign implant. Some options:

Undead may now find him unpalatable! Perhaps the salt and residual traces of negative energy mark him as less of a target than his juicier, more vital comrades. This could manifest as something like the Dead Truce.

If he can embrace these energies, he might find himself able to turn the effects outward, and make his salty presence repulsive to witches, undead, spirits, or fiends. As a negative-energy-based power -- and to keep it from acting as a turning -- I suggest that, if he manages to learn this trick, it only affect living beings: hags, devils, demons, blackguards, etc., etc. Of course, angels might find it nasty as well. This would probably require trial and error, and maybe a feat or spell slot or the like, depending on his base class.

Is there time yet for him not to have noticed some physical changes, like being really thirsty all the time? How about potions? Perhaps he can absorb surprising quantities of liquid for some reason... drink a lot, and not get drunk? Resistant to imbibed poisons? Potions and poisons at half effect, due to the absorbent material in his bloodstream?