My guess is that is an electric chair and the controller for it is under his right hand but he’s ambulatory so he needs the cane. Likely it’s not comfortable to hold it over his lap or up off the floor. Being disabled leads to using work arounds that don’t always make sense to able bodied folks. Holding a cane still might hurt more then keeping it in motion. Holding it over his lap might interfere with his hand. He could have balance issues and the cane helps him keep orientated. He could just be stimming. Does the why really matter?

HA! Jeep drivers will tell you that light just means everything is functioning as normal.

I have a lap desk similar to the one below. Easy to pick up or put aside as needed.

Edit: You should also consider tackball mice. They are great in limited spaces.