Why didn't frodo and company capture Sarumon and worm tongue?

I love the answer above and definitely think this is part of it. I also think it also serves as a good example of the influence of 'good' rather than 'evil', that runs through the book. By not capturing and essentially enslaving Saruman in any way, they are essentially trusting the Istari the opportunity to do better and once more find his true purpose on Middle Earth. The fact Saruman almost immediately travels to the Shire to enslave the kin of those who had 'freed' him, shows just how how far he has fallen. When the hobbits return and break this enslavement, the fact that Frodo then argues to free him again, only shows how far his character has come in an opposite way. After all, Frodo's initial thought when hearing of the story of Gollum was to wish for his death when Gandalf first told him of his story in "A Shadow of the Past" way back at the beginning of his journey. After everything the Hobbits have endured, the fact they can forgive Saruman when returning to their beloved Shire in hope of a peaceful life after all their trials and torments, not only highlights their character development, but also perhaps underlines the true passing of the Shadow and its influence in a meaningful way?

I think that they let Saruman be out of respect for what he once was.