There’s a major difference between expected betrayal being part of the rules of a game, and gaslighting groups of children into competing under false pretenses. Does playing by the rules of BSG or Saboteur guarantee a loss for the team that by the rules should be winning?
The analogy would be appropriate if BSG was a competitive space fleet management game and some players decide in advance to make it a meta-game to join and sabotage each fleet without telling anyone of their intentions, leaving everyone else playing the ”fake” game while they at the end reveal the ”real” game and that whoever lost the real game actually won and vice versa.