I think you're getting things a bit backwards. The tale already portrays peer pressure pretty damn well, because it's about how a lie gathers strength when, through various pressures, it causes people to use their intelligence not to pierce the lie, but rationalize and perpetuate it.
The child breaks the illusion without outsmarting anyone. The child does not comprehend the lie, has not worked out logically how to maneuver the swindlers into a position where they must confess, none of that. The child simply says what he sees, just as anyone else in the story could have done. What's different about the child is that he is immune to the rationalizations that others might have used to preserve the lie. A beggar could have done what the ministers could not, and speak up with no fear of endangering his occupation. But people would have come back at him with "and that's why you're not fit for anything but begging," and the lie would have endured.