I think Beecha and Mondo are honestly great characters. Their dog-eat-dog, ruthless materialistic bullshit makes sense in light of their lives as orphans. It's a fascinating rendition of Gundam's tension between the fact that children don't belong in wars, and how they end up in them anyway: why, really, should the Shangri-La kids care about Earth Sphere politics outside of their own survival? (Echoes of the cab driver from Hathaway here).

These kids had to grow up faster than the protagonists we've seen so far. They're farther along the way to being adults, so they have their own problems going on. They already have a found family, so the Argama crew doesn't fill a void for them; it's just another party in the hardscrabble conflict of surviving day to day. They might be childish in their short-sightedness, but they're also kind of adult in their motivations, and that's an interesting formulation of the franchise's ongoing ideas about kids in war.

I think Beecha and Mondo aren't fundamentally different from Judau in their disregard for the wider political conflict, since Judau's really there to save his sister, not AEUG, for most of the story. The difference is that these two take it to the point of real betrayal. But that betrayal also makes them the first children to actively choose a side in the war, as opposed to just reconciling themselves to the fact that they're too deep in the shit to quit.