If you are using the spreader arms that I think you are using then the salt was not a very large factor in this.

The proctor spreader arms use a stainless steel thread inside a aluminum bus. Those two materials will corrode in a Galvanic sense even when no kathelist like salt is present. This is always much more of a problem with threaded connections then say rivetted connections and the opening between the threads and the bus is just so small. Even a small sand grain can jam up a thread.

I found that the oxide formed can be broken down quite easily when heating the fitting in water or even submerge it in warm vinegar.

This may be worth a try.

But anyway, my main point is that it will happen again and there is nothing you can do about it apart from creasing up the threads really good before assembling, with waterproof crease or just replacing the turnbuckles with stainless/stainless. The first option only slows the creation of oxide down, only the second solution is a real solution.

Good luck !

Wouter