Even though that was the case, suppose a Martial Master discovers him, they would be able to remove the influence of the Naipa on him. After all, the Naipa wasn't part of their race.
But the same thing couldn't be said to be possible if the cause of the Elemental Poison was a Kalki. In such a case, a Martial Master wouldn't be able to eradicate the person's feeling of wanting to submit to the Elemental Poison caster.
And now, upon seeing the boy, both Re'Kha and Re'Gra knew that they couldn't leave him alone. They didn't wish for him to defect to the Naipa and live in hiding and plot against his brethren for the rest of his life.
So, they continuously injected Water Qi into his body, slowly watching as his body began to absorb some of the ambient Water Qi unleashed by the Water Qi Essence.
Body of Water!