Think about it:
The KC-Superman has been catapulted to a world, which in his eyes must be 1000x times better than his own. He believes all of his friends to be dead. Now we know how KC ended and the bomb definitely didn't destroy the world. So is KC-Superman telling the truth, is he wrong or is he lying?
My theory is that when the bomb exploded on E22 along with Starman's grav powers, created a wormhole that propelled Superman and Starman to New Earth. From Superman's POV his planet is dead. Somehow, he returns to the exact point the bomb exploded. Pissed off, probably that he returned but his current journey on New Earth gives hiim the inpiration to create a near Utopia on E22 ..... which I figure the current LSH is from. If not E22 that E51.