So if we assume that the Burton/Lill/Jon group hadn't yet cemented its alliance with the Darrah/Tijuana pairing, then everything that happened makes sense. Darrah and Tijuana certainly wouldn't have wanted to risk pissing off Rupert, lest he boot them before Ryan-O. Ryan-O literally was knocked out of the game with the first five coconuts that were placed, and he took his one shot at Christa, who we now know he personally dislikes pretty intensely. Not having the Burton/Lill/Darrah/Tijuana thing firmed up, he wouldn't know he had the votes against Rupert, so he wouldn't do it, either. Christa and Sandra appear to have retreated to their position of knocking out Ryan-O and then moving on to Rupert and Burton later, whether before or after knocking out Lill, Tijuana, and Darrah. Burton and Lill, I think, played this to give away as little as possible about their intent. They played just to avoid pissing anybody off, playing at coconutting each other and irrelevant people like Tijuana who didn't need immunity this week anyway. That suggested to me that they're still plotting, but not ready yet to move against Rupert. I just think the Darrah/Tijuana group hadn't hooked up with the Burton/Lill/Jon thing yet, so they didn't know for sure they had the votes. Having already seen one person go after Rupert and lose, they figure they might as well wait another week, considering that Ryan-O is a politically risk-free boot with which to go along. Furthermore, Rupert has absolutely no idea that any of this is happening, so it's pretty clear that there's not much chance that he's going to find out and come after them if they wait until the next tribal council. I think they just decided that there was little risk in waiting three more days until the whole deal was nailed down.