Interesting discussion.    My understanding is that a maggot refers to a dance with an unusual dance figure - the "whimsical fancy" definition.   Mr Isaac's maggot has the unusual trip around your neighbor. Corelli's Maggot has the unusual double gating figure.

There was a period of time that people thought that brilliant flashes of inspiration were caused by maggots nibbling on your brain. That's how the two definitions connect.