They left -they walked away from it all. It's like the adult child who turns their back on their parents & cutting the parents out of their lives, coming pack after the parents have died excpecting/ demanding a cut of the deceased estate.But what about Son'a claims to the planet and its resources? Many were born there so the planet is as much theirs as it is the Ba'ku.
Star Trek: Insurrection said:PICARD: You brought the Federation into the middle of a blood feud, Admiral. The children have returned to expel their elders, just as they were once expelled.
Doesn't sound like the Son'a were offered much of a choice.