Nura immediately shuts the curtain just a bit so that Katara is obscured from the looks of the other women in the dressing room. She shoots a particularly nosy one a look and then turns her attention back to Katara.
While nudity is something not so taboo in the 31st century as it is in the 21st century, Nura knows that it is uncouth to be nude (even briefly) in public in the 21st century. Katara, however, seems to not be aware of this at all. Thankfully, the curtain, and Nura's body, do good jobs of keeping Katara shielded from the criticizing eyes.
Re: Clothes Shopping
While nudity is something not so taboo in the 31st century as it is in the 21st century, Nura knows that it is uncouth to be nude (even briefly) in public in the 21st century. Katara, however, seems to not be aware of this at all. Thankfully, the curtain, and Nura's body, do good jobs of keeping Katara shielded from the criticizing eyes.
"How does it fit?"