This is probably just something RJ thought of when he was conceiving the BT. The may or may not have ever thought of a use for any special properties, but it is the kind of thing that one would think of when brainstorming the creation.

I am sure his notes (compiled over 20+ years) are full of irelevent little details (such a character's favorite color or lucky number) that have no way of making it into a story, but flesh out the world solely for the author's writing process.