If the abyss demons were left alone like this, with no other creatures as food, they would devour each other, and Axelle didn't want such a thing to happen.
Thus, as he incorporated those low-intelligent creatures into his domain, he quickly bred a lot more livestock for the abyss demons.
The transformer domain master didn't know that many creatures inside his domain were taken away and assimilated into Axelle's domain.
Once a domain was assimilated, that part of the domain would be lost forever unless the domain master re-created the lost areas, which required more energy and time than just fixing the damage from a completely broken domain clone.
Some creatures in this man's domain were gone, and Axelle happily integrated those creatures into his abyss domain so that they could become food for the abyss demons in his field.
Axelle didn't feel any guilt for doing something like that might endanger other people in this world.