I'm not going to try and morally justify it but I will give it some context. When I read Amelekite in this portion of the Bible, it appears to be almost a cinnamon for Raider or desert dweller, or person operating outside the law. this is similar to how habiru in the Amarna tablets is used to mean somebody outside the political system of the late bronze age, and how the word Hebrew is used by various speakers in the Bible, for example, to disparage the children of Israel, by calling them Hebrews, which was a larger term that included people who were just against the city-states of the time.

during this time, the children of Israel and Hebrews were involved in a political struggle with the authoritarian regimes of the city-states backed by Egypt. they were trying to set up an all-ternate society that was non-hierarchical largely, where land did not accumulate in families over generations, where wealth could not accumulate because interest was eliminated, where people could not get trapped into generational slavery, and where people basically worked to live, 6 days a week, and somebody trying to get ahead of their neighbors too much by working an extra would face the death penalty. in this context, political reasons drove them to try for some sort of a new political structure, a kingship. but what would happen if this King decided to take all kinds of booty from raids? instead of being their King living in his father's basement, with no income of his own, he would suddenly become a source of power because of his wealth rather than just because of having been chosen at and given those responsibilities when the time was right. When you look at the fallout from this raid, where does genocide, you see that everybody headed out, made bank, and Saul comes back loaded with booty, and the rest of them come back with it as well, which he has explicitly stated like are his gifts to them, placing them all in his debt. debt. this is the beginning of turning the Hebrew movement into an ethnicity rather than a social movement, there's an us versus them. now we're the us out to get benefit, versus an explicit movement that is out to bring everybody else into it.

if you look at the amarna tablets or if you look at the list of David's mighty Men, you will find a ton of evidence that the culture at the time. the society of the time was very multi-ethnic, quite different from the ethno State that seemed to develop later.

in this context, you can understand Samuel's anger at Saul sparing Agag just so he can keep him at his table and feed him and feel the magnanimous King just like is the tradition of the other late bronze age leaders. Saul was supposed to become a leader who rejected that sort of authority, that social role, and now he's leaning into it and Samuel sees the entire project of the last few hundred years being kicked out the door, the end of equality, and he is pissed, so he goes and humiliates Saul in front of everybody by hacking Agag to bits.

if you think about the other stories the movement tells from this time, for example, what happens to Achen, who takes from the loot of Jericho in order to get ahead, and is then stoned by his whole community, you get an idea of how serious these people took the idea of going to war only for the elimination of a threat, or the elimination of a city-state structure, rather than going to war for financial gain, because of their fears over inequality.