If an empty self-driving wheelchair were on its way to pick up its owner, would it be OK for a pedestrian to block its way?
It might be immoral, but certainly not illegal. But, what if the person it was driving to was planning to use it to commit crimes?! Then would it be okay?
There are no self-driving wheelchairs, let alone ones driving outside.
And in what world is it possibly driving around empty? Where's the owner, crawling around on the floor for fun?