Obviously, the holoship was never going to reach its destination, as the Ba'ku would then get a chance to reveal the truth to the Federation.
The planet would've been stripped of the radiation and the S'ona long gone by the time the Ba'ku realized anything happened.
The case appears airtight. The Son'a were out to kill, and there was no way they could not kill and still expect to survive.
This is utter bullshit, Timo. No where is there any hint of this being anything other than a straight move until Picard gets involved and starts using the Ba'ku men, women and children as human shields. He came far closer to getting them killed than Ru'afo did. You might want to go and revisit the film.
If it was about killing, the S'ona could've simply went in and wiped the Ba'ku out and set up shop in the Briar Patch and Starfleet would've never been any wiser. If you're intent on committing a crime, why complicate it far more than it needs to be?
Not to mention, Ru'afo isn't necessarily a simple thug. Moving the Ba'ku to another planet without their knowledge, so they can die slowly while he enjoys the benefits of immortality strikes me as a pretty delicious (if complicated) revenge.
I don't think he necessarily needed the Ba'ku to know he was the one who doomed them, just that they were doomed in the first place, and he would live on.
Would he have simply used the collector to kill the Ba'ku if the Federation hadn't been involved? Possibly. But once they were involved and brought the holoship into the picture, I can see him being okay with the Ba'ku just dying "naturally," as long as he gets his Fountain of Youth.