Protecting is one thing, but this way is no different than keeping her prisoner. With her innate talents and apparent mana reserve, we may have a Wild Mage in the making. Even worse if when she finally gets out and knows nothing of the world, some unscrupulous people will be able to take advantage of her naiveté. Treating someone like a doll in a display case only protects them from physical harm, but can slowly erode the mind and spirit.