Why would Yoda and Obiwan go into hiding at the end of episode 3. They believed Anikin to be dead. Did they think they wouldn't get another shot at at Sidious? Just biding their time for the Empire to weaken to make a move? Maybe they hoped other Jedi would survive and they could regroup. You would at least think Obiwan or Yoda would finish Vader when they learned he survived. What would make them think the Twins would be able to get a shot at Sidious?