Owen's an interesting antagonist. Seems like he's held onto some sense of morality and basic decency despite very much being a villain.
@Doomroar
Also, it probably would have been a very bad idea to draw iron on 'mom' when he's on a murder high and still has a ton of guns on him. Especially when the objective they came for is right there in front of them. A time and a place to sort that out later, I imagine.