Morally wrong/rotten… depends on the society. In our “modern” (depends how you look on things) society, this might be considered wrong, but in some tribe somewhere, it might be normal as you or I going to work in our suits.
Regarding legality, it’s probably not legal, since most laws that prohibit/endulge this or that are passed for adults, not minors, so the law is probably meant for adults only. Minors are probably excluded from this, so they should wear a bra/swimsuite.
My 2 cents…
I’ll bet you any ammount you want, that’s not brass. It’s iron with brass coating.