A fruit whose seeds lie packed together is refused because every seed is a soul, and the commentary's example is the pomegranate.
Bahu-bīja, many-seeded: the reason is the count. A single seed is one body with one soul; a fruit with seeds pressed against one another with nothing between is that many bodies swallowed at once. The modern lists set a boundary the verse does not, admitting the fruit whose seeds are held apart by a membrane, and they argue over which fruits fall on which side; the atlas draws the rule and the commentary's one example. Brinjal is on the plate for the same reason and one more.
The twenty-two, laid by their reasons - Many-seeded fruit highlighted