I'll just leave this here:
Admitting that there's a very wide diversity of beliefs under the "Roman Catholic" banner - historic Roman Catholic armies have been eager participants in well-documented battles for the past 1,500 or so years. I'd assume that Tolkien would have had a wide variety of perfectly historic Roman Catholic arguments to chose from, to justify his fictional slaughter.
(If I recall, the orcs slaughtered in LoTR are pretty much all soldier or near-soldiers. Do orc women, children, or other non-combatants ever appear in the story?)
In many ways, that Wikipedia article feels like a Hays Code-era whitewashing of Roman Catholicism.
He really did struggle with this, re: the origin of the Orcs, whether they had souls, whether it was ok to default to massacring them without second thought, etc. He never really resolved it.
Most Tolkien fan communities are aware of this dilemma, it's one of those well-known things, along with "did Balrogs have wings?", "couldn't they just fly to Mount Doom and drop the ring?" and "why did Sauron need to put his power within a ring, anyway?".
My issue is with the Wikipedia article's heavy identification of JRRT's personal dilemma with the Roman Church and its doctrines. Historically, for that Church - one could just assume that the orcs were Protestants, so slaughtering them was perfectly okay. https://en.wikipedia.org/wiki/French_Wars_of_Religion
If the allies were counterfactually sensible enough to fly the ring to Mordor, Sauron could have been counterfactually sensible enough to station an Orc/Troll Battlegroup at the Sammath Naur, with a Nazgul combat air patrol.
(Vs. voice-of-canon Gandalf makes it clear that anyone seeking to destroy his Preciousss is simply beyond Sauron's Vile McEvil worldview.)
In fact, when Gandalf catches up with Aragorn/Legolas/Gimli in 'The White Rider' chapter, he explicitly tells them that Sauron has committed a major strategic blunder: attacking too early, as soon as he thought the Ring was in play. If he'd kept some forces back to guard Mt Doom, he'd have been alright. Especially because, as later becomes clear, Mt Doom isn't a normal volcano where you could just lob the Ring in from your low-flying eagle. The Cracks of Doom are in a chamber deep inside the mountain.
Quoting Elrond during the Council at Rivendell:
> “It has been said that Dragon-fire might melt and consume the Rings of Power, but there is not now any dragon left on earth in which the old fire is hot enough; nor was there ever any fire, save the fire of Orodruin, that could melt the One Ring.”
Also, the Dwarves that took the One Ring for melting would have likely fallen under its influence, postponing the destruction and ultimately keeping the ring as a keepsake, tool or weapon, like most living creatures would... except for some brave Hobbits, which took a longer time to be corrupted.
More fundamentally, this is not the kind of mindset with which Tolkien wanted us to read LotR. It can be done for fun, but if done seriously, it'd be missing the point.
My own opinion is that debating this is missing the point. Tolkien was about the hero's journey, which necessitates the hard path to victory. It's not at all about flying a modern superweapon into Mount Doom; that's too literal a reading.