Sorry about the wonder poodle.

I would go with the direct approach. My friends all know how I feel about my bikes -- they don't go on roof racks or hitch racks either. [edit: the bikes, not the friends ] They all know and understand that it's important to me, while not to them.

I vote for the direct approach. "Hey, I know you like to touch the artwork, but it's very precious and valuable to me, and it makes me nervous to have it handled." Then turn it around, "I hate to even touch it or move it myself!"

How can anyone argue with that?