I have been trying to think of analogies in other areas , but the easy of duplication of things digital makes this difficult. However, props, morphs, figures, textures are tools. They are not a recorded performance, or a book, or a painting (a render is). Trying to control how a tool is used, is like Thomasville trying to say that a chair they sold or gave to Goodwill can not be used in the background of a picture. If the photgrapher claimed to have built the chair himself, this s something else.