Excellent post. As a ‘by the way’; Superman killed Zod (and two others) by kryptonite poisoning in the comics circa 1987.
He did at the end of the silver age, but he gold krypto’ed his powers away as penance. And Byrne had him do it (your reference) but that story kind of dissolved in canon and even then he banished himself into space. “The Ending Battle” with Black Manchester is the quintessential *modern age* “Superman Does Not Kill” story. But that’s just so boring to today’s hipster morally sophisticated consumer.