Your argument contradicts the primary idea of Nikhil's essay, which is that we casually display objects that contain all three types of matter. While it is true that we may purposefully display objects with a specific purpose in mind, that purpose is still to casually display the object. Whether it is done out of aesthetic pleasure, commemoration, or to signify a meaning or value, we are still casually displaying the object in our homes and spaces.
Although you make a valid point by suggesting that we choose objects carefully when displaying them, this doesn't mean that we aren't casually displaying all three types of matter. In fact, even if we choose objects with care and consideration, it is still done with the intention of displaying the object casually, hence Nikhil's original statement remains true. Thus, if we are to accept your retort at face value, then the conclusion must be that we do, in fact, casually display objects with all 3 types of matter. UrRong; we do indeed casually display objects containing all three types of matter!