Molecule Man was a bomb the Beyonders had prepared for their experiment.
Even if the two Earths had not been destroyed after colliding, they would have detonated the bombs and wiped them out completely, emptying the "experimental vessels."
Doom had stolen quite a few Molecule Men back then, including the one from Earth-40K. He had taken them to the Multiversal Library, but Su Ming did not know what he had done with them afterward, nor could he be bothered to ask.
However, the many worlds that had lost their Molecule Men were regarded by the Beyonders as having lost their insurance. That was why Cartographers descended upon them, allowing for manual self-destruction at a critical moment.
The Cartographers were cannon fodder. No matter how many died, no one cared. But to ordinary humans, Cartographers were nearly invincible gods in the Third-Dimensional World.
The nameless Earth where Deathstroke and Death currently were had once been the home of one Molecule Man. That person had been taken away by Doom, and not long afterward, the Cartographers descended here.
Su Ming's goal was to find these Cartographers, then wear CCU's face and let them "kill" him.
They were easy enough to find. New York City was only so damn big, and locating a few outrageously arrogant alien robots was effortless.
Even without Strangle or Cloak, Su Ming could practically say he had no weapons at all. But that did not matter. Having a brain was enough.
The Beyonders never explained what they did, nor did they bother concealing anything. This was the information age. Pick up any phone off the street, search online, and you would know where they had landed. It was the era of citizen media, after all.
This truly was the apocalypse, but electricity and the internet would not be