It doesn't really matter if it was in the beta, you didn't need to give away the costumes for free. If you find a glitch you let Mm know, or if they aren't responding you make a thread in the beta forums explaining how serious the problem could become if it doesn't get fixed to try and get the attention of the community. You don't need to show us how much of a problem it can be.
It also doesn't help that the glitch made it through to the full game. Or at least the costumes did; as soon as the game was released everyone had fake crowns.

