Augusta was absolutely capable of doing this. And when it came to mortals below the divine level, a Sovereign could kill them with a single thought; there was no need to send an avatar at all. Hadn't even Mid-Gods been able to send avatars to the Yulan Continent in the original story?
But for a Sovereign to kill a god, he had to appear before his target in person and wield Sovereign's Might to do the deed. If Beirut really sent an avatar to the Radiant Divine Plane to kill the Radiant Overlord's family, it would be shattered before it even arrived.
Besides, the members of the Augusta Clan had all been adopted by the Radiant Overlord to serve as a smokescreen. They weren't related to him by blood at all. Even if the entire Augusta Clan were wiped out, the Radiant Overlord wouldn't feel any grief. He could always adopt another batch. The only real loss would be face.
Beirut was a Sovereign, not a babysitter who could look after mortals every day. What he needed were people who could fight alongside him. Besides, a thief might be caught after a thousand days, but who could guard against one for a thousand days? And if the Radiant Overlord really killed every mortal on the Yulan Continent, life would become even harder for him and his few remaining companions.
At that moment, Hodan picked up where the Radiant Overlord had left off. "Enough talk, Beirut. Bebe is in my hands. If you don't want your God-Eater Rat kind to go extinct, swear to the Overgod that you won't attack our Eight Great Clans. Or are you hoping another God-Eater Rat will appear in this world?"
For a heaven-defying divine beast like the God-Eater Rat, even the appearance of a second