Short Cutfinder was a good joke in the Golden Era of Stunts racing and a long-lasting mystery. I've never thought that it was BJ.
It is hard to call it a ghost. IMO a ghost is a.) interfering the results of other pipsqueaks - not true, since SC's time was never threatened our times OR b.) invoked by competition managers to increase the number of pipsqueaks in his competition - not true, BJ wasn't the competition manager and he had other goals with it.