> "You clearly are not arguing that QBO may not exist, for lack of any proof. You are arguing for the existence of Lunar Forcing."

An elementary Newtonian physical model would suggest that the effect is there, the question is whether the effect is strong enough. The Chandler wobble is a prime example. If I gave a spinning top a periodic nudge orthogonal to one of its poles, after a transient precessional wobble it will stabilize into a cyclic wobble that matches the nudging period. Any freshman physics lab experiment can show that -- it's called a forced response as opposed to the natural response. It also occurs for any electrical circuit -- and it's essentially why what you hear through an audio amplifier is a scaled and filtered approximation to the input signal (if it was a nonlinear response, it would need to be decoded, as in the Mach-Zehnder-like modulation found in the ENSO model's forced response).

The question is why after ~130 years since Chandler discovered the Earth's wobble, why hasn't this simple relation of the moon and sun doing the nudging been documented anywhere?

Several Russian teams seem to be on the same intuitive track, yet they can't seem to get the math right. I responded to one of the reviewers of my submitted paper here: see reply AC2 https://esd.copernicus.org/preprints/esd-2020-74/#discussion

And there's the case of Grumbine from NASA who was also kind of on the right track, but couldn't quite grasp it either

Look at all the comments that I added to Grumbine's blog post -- this was 4 years ago and not a peep in response !

I'm willing to keep hammering on this rather elementary explanation as it's bordering on absurdity at this point. Apparently it was Munk and McDonald in 1960 that claimed that externally applied gravitational torques could not cause the wobble, see https://www.google.com/books/edition/The_Rotation_of_the_Earth/klDqPAAACAAJ