PaulP: "ENSO is a straightforward tidal forcing."
Lets carefully define "straightforward tidal forcing". A boat docked at a seaside port subject to lunar tides rises and falls with those tides. This is highly predictable forcing, with very little uncertainty.
ENSO is not that straight forward. There are many sources of non-tidal variation, of noise, of uncertainty; and supposed lunar forcing, with many unexplained aperiodicities in the data, is not as coherent as the boat case.
PaulP: "Earth sciences is not a discipline that attracts the curious from what I have discovered."
That's fortunately untrue for Lunar Tidal Geophysics. Galileo, Newton, Bernoulli, Laplace, Napier, and on and on to our time is a who's who of top tide scientists. In fact, without curiosity, one hardly could become a scientist. Its unclear what a valid test is for identifying non-curious Earth Scientists. You have barely sampled the Earth Scientist population, so not finding the curious could be a statistical Feynman-Point effect.
The problem seems to be that ENSO and QBO are so complex that they are not even rigorously defined (the Elephant problem). ENSO, for example, began as sea-surface temperature oscillation, and then a wind oscillation added. These are not the surface altimetry data parameter lunar tides are traditionally represented by. Given these very disparate properties, there is still no mathematical-physics proof that excitation is being confused for forcing, or vice versa.
This is very interesting Earth Science. I am learning a lot. Surely ENSO-QBO mysteries and controversies will further resolve by continued curiosity...