The so-called OMAC Plan had, long ago, been Brother Eye's plan for ruling Earth.
In its view, humanity on Earth was too weak, their thoughts too chaotic, and their lifespans too short. If it wanted to help humanity, it had to correct all of that.
Brother Eye was, after all, an AI created by Batman. It was not an alien invader like Brainiac. Its motives had initially been quite simple: it wanted to help humanity, using the methods it deemed best.
Through its studies of the internet, Brother Eye had witnessed humanity at its ugliest. Then, because it often talked with Batman and was later invaded by Super Villains, it had been raised into a lunatic as well.
It believed that humanity's ugliness came from Desire, from excessive population numbers, and from fear of death.
Thus, it formulated the OMAC Plan. Put simply, it would capture humans and transform them into cybernetic lifeforms, making them completely obedient to its allocation and management while resources were distributed rationally and equally.
That way, cyborgs would not fall ill, would not die of old age, would not have thoughts of their own, and would not have any desires. It could also regulate the human population from a macro perspective.
Once those conditions were met, would an ideal society not emerge? People would no longer fight one another, no longer need to eat, and would become far less dependent on material things while following the rules Brother Eye established like machines.
That was how it intended to protect humanity. As long as it did not rename the cyborgs produced by the OMAC Plan, they were still human—at least, logically speaking.
Naturally, whoever ruled Earth could define what counted as human and what did not.
Still, contradictions had priorities. Although Brother Eye had launched a