Both are excellent points.I'm not sure how Cochran was supposed to just vote with "the other tribe" the first vote when they would not tell him who they were voting for. He had no idea they were voting Keith until the split vote. Then he knew who to vote for so that he could flip sides. It would have been different if they had let him know ahead of time however they did not since they were not sure they could trust him.
I was disappointed in Dawn who seemed ready to stand up for Cochran and flip as well so that she didn't have to pick a rock, until she won individual immunity and changed her mind. So she was ready to make a big game change as long as she was on the possible chopping block but as soon as she was safe she decided against it.