Not a joke. A practical design choice. He didnt want any delays associated with the payload. He didnt want a "failure" should his rocket work but the payload fail. He needed a known object, something that had at least gone through the vibration testing to ensure it didnt damage the rocket on launch. And he likes being rich. So he took the oppertunity to use the launch of one product to promote another. Nothing of this is funny to him. This is business.

Or he just wanted an excuse to go car shopping again.