Actually, it is different, becasue a render that is posted and used as a wallpaper is an original work that does not compete with sales of products because the wallpaper is not being used to create new images.
The tubes do compete with sales because they are providing a means for others to create new/derivitive images using a product derivitive that they may not legally own.
This subject comes up often in the DAZ forums and the answer is generally. "No, you cannot do that".