Tea would never forbid Laura from speaking if she wanted, it was just not part of her job to do so. While they were out and Tea was doing things with other people, her only job was to protect her. Being seen and not heard allowed her to focus on what her main task was. If she was distracted by conversation, she wasn't able to keep an eye on what's going on around them.
"So more casual and comfortable than dressy and stylish?" Tea commented as she looked her over. "I used to be the same way" She told her as she began looking over some dresses that were near by. Now that she had a style in mind, she knew what she was looking for.