Sometimes I see the structures of moments as jokes. In training actors and directors we often talk about Beats (or “bits” as someone alleged that Stansilavsky was actually saying with his Russian accent.) This whole Jephthah section is a curious beat and if it were a joke, it would seem to fall flat here. The punchline feels like it’s all at the top. Perhaps these quoted lines are a song and perhaps the melody provides a punchline that the strange vagueness of them doesn’t, but with the information I have in front of me, it sort of fizzles out.
Hamlet brings up a man who killed his daughter, calls Polonius that man and when Polonius accepts the offer, Hamlet blocks it and sings a nonsensical song. Maybe it’s a Monty Python sort of joke in which a man at a desk interrupts with something odd instead of ending the sketch.