Stephen explains the split-vote tactic.
What you did see: Jeff asked Stephen why he thought splitting his two-vote advantage was a good idea and the ex-castaway said he was fixated on outing Joe because it was his Second Chance opportunity to make a big move. However, he admitted that he didn't have the full backstory of information before making his bold decision.
What you didn't see: Stephen's heart-to-heart backstage chat with Spencer about whether they would consider themselves introverts or extroverts. He also congratulated Spencer on completing the "Step On Up" Immunity Challenge puzzle so quickly.