[anotherpaulg]

This is a very interesting, novel take on explaining the delayed choice quantum eraser. I think I can summarize it as follows:

The signal photon hits the screen, which is a measurement. The entangled idler's wave function is thereby constrained by that measurement, influencing the probabilities of later detecting it at each of the D1-4 detectors. It's not that the fate/erasing of the idler changes the already committed path(s) of the signal. It's that the measurement of the signal constrains the subsequent detection of the idler.

Two other high quality discussions of eraser experiments are by Sean Caroll [0] and Sabine Hossenfelder [1]. Like the OP, both Sabine and Sean demystify/debunk these experiments.

These three discussions all use different language to explain the outcome, which is clearly predicted by the QM math. Sean's article includes the gist of the math.

[0] https://www.preposterousuniverse.com/blog/2019/09/21/the-not...

[1] https://www.youtube.com/watch?v=RQv5CVELG3U