Burster of Bubbles, Destroyer of Dreams.
Just imagine the red offboard up here. I'll create it Real Soon Now...
Yes, I know a proper 18XX tile should have a tile number.
I think the intent of the quoted statement is that you can always run a Ghan even when you do not have another train. Specifically, if you have two companies with Ghans and only one regular train, they can both run Ghans, paying out and moving up the stock chart, while swapping the other train between them to satisfy the train ownership requirement.
Yes, this was precisely my intent, and precisely the maneuver I have used in the past.
If a company is actually running a Ghan and another train then they do need separate track, just like any other pair of trains.