I don't think the Baku are asses at all. That planet is their home, and has been for a long time. They have as much right to live in their home as you do yours.
I'm sure they would be amenable to the rings being studied, and might be willing to provide insights into it, were it not for the Sona.
If I were being kicked out of my home of hundreds of years, I'd be "an ass" too.
So it is wrong for the Son'a to use force to remove the Ba'ku from their homes, but its okay for the Ba'ku to use force to remove the Son'a from the planet? The whole story is based on a bunch of plot holes, the Ba'ku were a bunch of tech hating pacifistic, how did the Son'a lose to them in the first place? Why didn't the Son'a just establish another colony on the planet after losing the Ba'ku? Frankly the Son'a being random evil alien invaders who were just selfish and wanted to be immortal would have made more sense then them being Ba'ku.