Fell down the Youtube rabbit hole. Got into a back and forth with a couple of DCMU fan's. The crux of their argument was basically. "Superman should kill. His foes are generally insanely powerful warlords, or very powerful beings who have no issue with doing so" basically WHY Should Superman have to live up to the same standards as his foes.
This is the thing. Superman is basically a GOD. The simplest way I could put this is when Superman decides to kill, whether it be a super powered threat, The head of a major conglomerate trying to take over the world through political and financial clout etc...
HE WOULD BECOME A THREAT IN THE EYES OF HUMANITY!!!
Superman isn't beholden to any laws. any country/government, or any military.
He can do pretty much what the fukk he wants to. WHEN he want's to.
You cannot have superman murdering people. villains or otherwise.