That is true, but it doesn't changes the fact she is locking down any other store on MP with that including her own, rendering them unable to make new listings or change any. There are stores that don't have a inworld location and fully depend on MP running as smooth as possible. While this move protects her own inworld business it rips down everyone else MP business for the duration of the promo, and that is kind of playing dirty, maybe not even on purpose, but Catwa actually should know the effect such a sale has.
I like competition as creator, and i also like fair play... so i wouldn't do anything that comes with such a careless collateral damage