Considering they left to start their own interstellar empire, they were too much like prisoners now were they.
Ru'afo says they were exiled in the movie.
Exiled: expulsion from one's native land by authoritative decree.
Star Trek: Insurrection wrote:
SOJEF: A century ago, a group of our young people wanted to follow the ways of the offlanders. They tried to take over the colony and when they failed...
RU'AFO: And when we failed, you exiled us to die slowly.
They wouldn't have died slowly if they had simply been forced from the village. So the Ba'ku had to have the ability to force them from the planet and possibly the Briar Patch.
The movie was just very poor, in my opinion. It doesn't stand up under any type of scrutiny.