I think the difficult thing is how to enforce a “no minors in photos” policy, because there are obviously very fuzzy lines between what would and wouldn’t be deleted under that policy.
Personally, I feel like “no observations or photos where a minor (or probable minor) is the focus of the observation or photo” is kind of the best way to handle this – it’s clearly subjective, but it’s better to be explicit that it’s subjective than to say “no minors” and then have to figure out how to be completely objective about it. If there is doubt whether the individual is a minor, not much is lost by deleting the photo anyway. And specifying focus allows the obvious exceptions to a blanket “no minors/faces in photos” rule to remain on the site.
For example, hypothetically, I don’t think we’d want to delete a silly photo where a bird is standing on a toddler’s head and the observation is for the bird. Or especially a photo where a kid is just out-of-focus in the background.
There should also definitely be some kind of recourse for “observation photo is focused on a person, and that person does not want that photo to be on the website” regardless of whether the individual is a minor. A photo like that doesn’t currently break any rules, but the existence of the photo harms the goals of the website more than it helps them.
I also like the idea of blanket obscuring human observations – it doesn’t hurt the already-limited usefulness of “human” observations very much to do that, and I agree that it would be good for privacy reasons.