Why did he separate them? That's the easy way out. A pro way would be to have two domains within the same bead, one for the demon qi, one for human qi. A barrier would be between them. He could even allow the denizens within to breach the barrier with much work, in a limited manner, if the demons and humans wanted to interact, such as wage war with each other. That being said, it would naturally be morally correct to not carry the new demon domain with him but instead unravel/expand it into the void somewhere, so that it would be a normal place in the universe, not his personal possession whose fate would depend on his own fortunes.