I'm saying that you can't use that to argue backwards to say Ru'afo was always going to betray the Federation.
No, but I can speculate that it could happen seeing as Ru'afo threatened to blow up the Enterprise and the Son'a had no problem shooting Data just for finding the holoship, or the fact that the Riker just going to bitch at the Federation was what Ru'afo thought was enough provocation to attack the federation flagship with the intent to destroy it.
Ru'afo threatened to blow up the Enterprise only -after- Picard refused to release his people. The shooting Data bit for finding the holoship is a bit ambiguous as we never actually saw the events that occurred. If I had to guess it was because Data declared he was going to reveal it to everyone and compromise the whole operation. As for attacking the Enterprise, even then Ru'afo talked Dougherty into signing off on it when he had all the cards and didn't have to. Hardly the actions of a guy planning to betray the whole Federation.
Really the most villainous thing Ru'afo did the first freaking half of the movie was bleed on Picard's ready room carpet.