I'm sure someone with internal transmission knowledge could, but that's not why I created the thread. This is more of an "end user FYI" for people doing their maintenance. All past discussions i've found on the topic end without a resolution on the actual OEM recommended way to check the fluid.

If I had to guess, I'd say it has more to do with torque converter pressures fluctuating slightly with engine RPMs. In Park the RPM is more steady (for the most part) than in Neutral.