Where does the sophistry come in? "...while the number of soldiers killed has tended to go down, the proportion of civilians and noncombatants of all ages killed has skyrocketed."

"Tended" means generally, on the whole, for the most part. It doesn't mean everywhere and in all places. In the Falklands/Malvinas War I believe only three civilians were killed (by friendly fire, as it happened.) And there have been other exceptions. But if you take in the dead in Vietnam, or the Congo, or Angola or all kinds of other wards, few of which ever make the front pages, it's mostly civilians.