I believe he was trying to work out some deal with Sandra, out of what looked like depseration, and pulled the "I swear on my grandmother" card again. Perhaps he is going to think that the threat of Sandra being able to align the women is very real.
Going back a few weeks, Tijuana made one of the DUMBEST moves in the history of Survivor. By trying to punk out Jon with the threat of voting out Burton BEFORE it happened, she gave him a chance to scramble and work the deal with Sandra and Christa. Had she waited until after Burton was voted out, Jon would have DEFINITELY joined her and Darrah at that point if she asked him. And they would have probably been able to grab Lil as well. Instead she tried to make her power play early for no good reason, when a little patience probably would have guaranteed her top 4.
But it was also incredibly stupid of Sandra and Christa to decide not to vote Burton out because of Jon's plea. They should have taken out Burton while they had the chance. Darrah made the same mistake this week. They didn't even need a swing vote. If the vote was 3 for Burton and 3 for Christa, Burton would have been voted out based on the previous votes for a tiebreaker.
And going back several weeks, does anybody know why in the hell Tijuana and Darrah voted for Rhyno the week he was kicked out? That made no sense to me, especially when they all seemed so tight at that point. I don't see what they gained.
And while I'm thinking about it, why do so may of members of the two tribes dislike Christa? From what they've shown, she hasn't given much cause for all this apparent disdain.