I’m not so sure about this. Unless I am misunderstanding things or missing something obvious - I have a test user that is a moderator (staff), but belongs to a custom super users primary group (that does not have a flair) and I set up a custom image avatar for staff that shows up without a problem.
I believe the flair visibility to other users depends on these two settings here (I’m not sure if it should but it seems to when I test it with various test users):
