When the freed prisoner is returned, he attempts to convince the others of what he saw, and Plato backs out when they refuse to listen, so that he may tie it in to his own example, as though he has found the only higher truth. By virtue of his setup, there can be no arguing as to the validity of another "truth", because it becomes difficult to argue that there is another valid form of reality, of sunlight or voices, that we do not perceive. Plato designed his allegory to focus on the idea of truth, rather than the thought that multiple truths may exist. This fits well into Plato's theory of one higher truth, but it is a view not necessarily shared by all, and so makes weak ground upon which to base one's argument.
The reason for this is similar: fear of change. The fear of change is derived as all similar situations are; fear that comfort felt in one's present situation will be lost in the new situation. Possible benefit weighs very low in one's mind compared to tangible benefit. So the result is a lack of belief from those with whom the two characters normally associated.
Rather than simply accepting that they could have been wrong, the characters both look elsewhere to deal with this spurning of ideas. This is the point at which the stories diverge in path and view. "Allegory of the Cave" takes the stance that this enlightenment, the only real truth, must be shared with others without rest until all are converted. "Jumping Mouse" seems to say that one must