... Did they just kind of murder Phos? Because they just broke apart the most physically unstable one of them and scattered the parts so they would never come together again, which is the closest to being dead those rocks get.
As far as they know, it's entirely possible that it would be impossible to restore Phos, if even a single part is lost and/or impossible to recover. And they did it without court, trial or even letting Phos explain anything.
Fuck the earth rocks, the rocks on the moon are the only decent people around. Except for the jackass. You know who I'm talking about.