This study of crank inertial load may be relevant here. In particular the HL and HH conditions (low vs high inertial load when riding on flat ground). HL would be equivalent to a headwind and HH a tailwind.

https://rcnl.rice.edu/PDFs/jb2002.pdf

Key points are:-

1. There will be a lower crank inertial load when riding into a headwind at the same power.

2. Lower crank inertial load is associated with riders freely choosing a lower cadence.

I also think in reality that few riders actually do ride at the same power into a headwind. Most riders naturally increase their power like when going into a climb. In a tailwind it is very tempting to soft pedal occasionally, even when riding hard. A headwind is far more relentless, again like a climb.