Kizaru hadn't deceived Zephyr. After the Land of Light occupied the East Blue, Tobirama and Orochimaru had proposed conducting experiments on Impure World Reincarnation in the East Blue and researching souls.
This was, in part, a contingency plan the Land of Light's leadership had devised early on, after arriving in the Pirate World and seeing its enormous population.
The Land of Light had a limited number of ninjas. Letting them wear themselves down in an all-out war against the World Government would have been extremely unwise.
That was why the Undead Army created through Impure World Reincarnation had become, in Tobirama's eyes, the key weapon for wiping out the World Government's vast forces.
But the number of ninjas they could reincarnate from the Naruto World still fell far short of Tobirama's target.
So, naturally, experimenting with Impure World Reincarnation in the Pirate World and using its vast population to summon a sufficient undead army had become one of the Land of Light's strategic objectives.
However, since this plan violated conventional ethics and morality, the Land of Light had always carried it out in secret. Only a handful of senior officials knew the details.
Kizaru had chosen to reveal some of that information to Zephyr and dangle this prospect before him because he knew how much influence Zephyr had over the Navy's officers and soldiers. It was a trump card he had prepared especially for this occasion.
Zephyr reacted just as Kizaru had expected. As soon as Kizaru spoke, the old man, who had still seemed weighed down by age moments earlier, grew agitated.
Seeing Zephyr so excited he could barely contain himself, Kizaru raised a hand and pressed it down repeatedly, signaling the veteran Marine Admiral to calm down.
At Kizaru's gesture, Zephyr did gradually regain some of his composure.