Supposedly the Jews thought it was confinement and as a group had no certainty of impending doom. The less someone resists and the less a group is united the easier it is to deal with them. If you dont want your target to fight to the last drop of blood they need to think doing so for their personal survival isnt absolutely needed. They can be nervous and have suspicion or fears but the entire group should never be one hundred percent certain that they personally will die without doing their absolute best to a suicidal degree. True or not its a good lesson.