High chances that Oda, loving Kaidou, shielded him from a possible "L." We expected Kaidou to be severely injured after an extreme battle against Roger or Prime Garp and then eat the Devil Fruit to recover. By having him eat the Devil Fruit so early, even before possibly fighting, Oda effectively shields Kaidou from any potential "L." After all, the Devil Fruit narrows the gap between Kaidou and the strongest, and even without the Devil Fruit it was already unlikely that anyone could easily defeat him. Now, with the Devil Fruit, he is completely protected from that thanks to the significant increase in resistance and recovery.
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