Superman left.
He did not say he would join the New Krypton Empire and become the bridge that eased relations between the New Krypton Empire, the Justice League, and the superheroes.
Nor did he reject He-El.
But he knew He-El was right. This was the only way to prevent a battle between He-El and the superheroes from destroying Earth.
Most importantly, the superheroes on Earth, the Justice League, and the rest could not defeat He-El.
Even if they raised an army to attack the New Krypton Empire, it would only trigger an even larger world war. That would not be good for Earth.
He-El knew that although Superman had not joined the New Krypton Empire, he would certainly become the buffer between the New Krypton Empire and Earth's superheroes.
Furthermore, after the New Krypton Empire was founded, it would build friendly relations with governments around the world. It only needed to casually leak a little scientific knowledge and biotechnology, or give national leaders some genetic medicine that extended their lifespans. Then, if the superheroes dared attack the New Krypton Empire, governments across the world would accuse them of interfering in domestic affairs, and they would instantly become targets of universal condemnation.
He-El would not waste time arguing with them, nor would he need to fight them personally. He only needed other nations to issue condemnations and apply pressure. How many superheroes would still dare make a fuss then?
They could not beat He-El, and they would be played to death politically by him. Once their own countries stripped them of citizenship and put out warrants for their arrest, they would see just how many superheroes still dared abandon everything to oppose the New Krypton Empire.
He-El believed there would be some.
But... they would no longer be qualified to oppose