I have created a forum topic with the results of my research so far. It can be read here. Thanks to everyone who has contributed to the topic so far!
https://forum.inaturalist.org/t/preliminary-findings-from-a-qualitative-study-on-inaturalist-users-license-choices-show-there-is-a-substantial-portion-of-inaturalist-users-who-have-all-rights-reserved-by-mistake/52742