My main contention is that it's possible to construct a physical apparatus using visually observable non-quantum macro objects (like pairs of bar magnets) that pass through such filters with the same correlations shown by the blue line in the graph above. Such correlations would apparently violate Bells theorem, even though the objects were obeying classical laws of motion.

And it's certainly conceivable that passing through a slit could change the orientation of a wave, whether mechanical wave...

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSrnPB4...

or the wavefunction of a photon...

https://cronodon.com/images/Single_slit_diffraction_1.jpg