Kadara - Angara Settlers vs Charybdis Exiles [Possible Spoiler]

In all fairness, the exiles attacked Ryder first with the intention of killing ("screw it, let's just kill them"). I don't think Ryder was wrong for self defense.

I'd have preferred a different outcome too, but there it is.

Except that will never happen.  First, they were Exiles and so outside any AI jurisdiction.  In theory, they were under Sloane's rule, but they were further exiled by her to the wastelands of Kadara. That means they were loners in a lawless land.  They are accountable to no one unless someone chooses to enact justice/vengeance on behalf of those they harmed.  Exile itself (twice) didn't prove to be enough to make them actually learn to play nice with others.  Exactly when you do draw the line and decide they're too dangerous to society to be allowed to live?  Sure, we could try to haul them back to the Nexus to put in a prison cell, but it seems an unlikely thing to happen.  Thus, we're left with executing them for their crimes because leaving them alone doesn't work.