Definitely not allowed! Neither is the nose piercing of the female FA that you witnessed. They can not even wear the small plugs for nose piercings that make the hole “disappear” but keep it from closing up. Female FA’s may only wear one pair of matching earrings. Male FA’s may wear one stud earring in one ear.
I’m guessing they pursued the pax list prior to putting these in while in flight to insure no one was onboard that was AA upper mgmt and I’m willing to bet to make sure no non-revs as well, to lower their chance of getting turned in.
No visible tattoos allowed either.