After the Supreme Mage suggested dealing with the Zeus Kingdom by himself, it was later on agreed that the Ultimate Knight would stay in the kingdom to protect it in case something happened.
Well, if there was something that indeed happened in the Gaia Kingdom, then even if the Ultimate Knight wasn't dispatched, Iris Aria alone was invincible against mortals. Not to mention, John Skier could use his authorities to temporarily acquire the power of Perfection Realm Peak Stage.
If there was a place that had the most powerhouses aside from the god domain, then it would be the Gaia Kingdom.
Even if the Zeus Kingdom was rumored to be the strongest kingdom, that was before Allen and his chat group members supported the Gaia Kingdom. Now that they supported the Gaia Kingdom, the Gaia Kingdom was the strongest kingdom in the entire world.