One should not sell bombs to a government that abuses human rights, which means murders a man without using one of the bombs.
If Saudi Arabia had murdered a man using a bomb, it would be fine to sell Saudi Arabia more bombs.
But Saudi Arabia murdered with a non-bomb weapon, and so shouldn’t have bombs anymore.
One should, in fact, bomb people whose government abuses human rights, which means murders children without using bombs.
Syria allegedly killed children using chemical weapons, and so Syrian men, women, and children should be bombed.
Killing millions of people in wars, year after year, as long as it’s with bombs, is justifiable because the Good War was justifiable because although the war killed some 80 million people, about 13 million of them were killed in German camps which doesn’t really count as war and is therefore not justifiable, especially for 6 to 9 million of them, although those are precisely the ones who could have been very easily spared by permitting Germany to expel them, something none of the governments whose warmaking justifies all future wars would agree to.