RC is the only person that Abi had any hand in putting in the jury. Everyone else was put there by the current power alliance. The jury doesn't forget that. The final vote isn't about who played the best or who deserves it the most, even as much as they like to pretend it is. It's about getting revenge on whoever kicked you out.
Sandra was the same "grumpy around camp/she'll never get votes" type player, and she won.