This Wikipedia page lists common sequestrants (with respect to food science). As stated on the page:
A sequestrant forms chelate complexes with polyvalent metal ions, especially copper, iron and nickel, which can prevent the oxidation of the fats in the food.
To me, this behavior makes sense for every example listed except calcium chloride. I can certainly see chloride complexing these metal ions, but even then, I typically don't expect the chloride ion to reduce catalytic capabilities much.
I assume the calcium cation has an effect on these processes somehow, too. Otherwise, I would expect regular table salt to have the same effect, but, while discouraging bacterial growth, I don't think sodium chloride reduces the rate of oxidative rancidification.
Could it be as simple as the desiccant effect of calcium chloride keeping the polyvalent metal ions from dissolving? It would seem like a massive amount of calcium chloride would be needed to have the desired effect if that was the preservation mechanism involved.