I see the logic here. But why, though? And technology is everywhere in non-human nature. While I think our technology and civilization is unlike anything else here, it’s still on the spectrum of nature’s exercise of community and technology. Are we really that special?
I think this heads towards the whole “Prime Directive” line of reasoning.
P.S. Eloi > Morlocks, of course. ;)
There’s no logic there. Just a faith in “potential”.
It is arguable one way or the other whether civilizational humans have caused more happiness or more suffering for Earth (all of us lifeforms combined). So the only way to call such a thing “morally reprehensible” is if you assume that Civilization will eventually evolve into some awesome, fantastic, space-faring, all-needs-met, stewards of the near solar system fantasticness.
I would wager than as soon as a technological civilization is born, it's morally reprehensible to let it go extinct, since it no longer is at the full whims of evolution. It's complex issue, so many people would wage otherwise, and only a jury might reach a conclusion. The case is moot when said civilization can avert extinction by their own hand, though.
I don't know about two technological civilizations in conflict, like sapiens and neanderthals. Would it be morally acceptable to let them go at each other, even if the fittest extinguishes the other?