Is the Manciple's Tale Baseless Fearmongering? Yes!

The original essay is here. This basically explains the ending in terms of the Rhetoric of Drugs.

The choice to end this essay on the Manciple's Tale served two purposes. The first was that it was a self-negating. It is a story, but it's a story about not telling stories. This makes it similar to the Rhetoric of Drugs:

• The story is "pointed at itself" in a very specific way
• The story is meant to produce an effect
• The story has a zero truth value
• The sentence imposed on the crow is false

So, the story mirrors the Rhetoric of Drugs insofar as it's designed to produce a feeling of fear. It's about being very carful what you say, even when you're right. 

Now, I can tell a different story about someone who rats on a cheating spouse and is rewarded with $20,000 grand because they're a private investigator and that's their job. This would essentially render the fear inert or at least give the individual the sense that quietude was not the only possible solution to this problem.

The Maniciple's Tale is anti-narrative narrative.  The function of the narrative is designed to make you afraid.