I belive CMP that is not totally correct.
"Sure, we will have to pay Cliffs a price to get our stuff to market on whatever system they put in place but they can't deny us."

They can own most transportation means but to own a road would require a special permit. Only exception that I know of is the private Highway 407 by-pass in Toronto which apparently is now considered a mistake by many due to privatization?

Roads are public in Ontario and usually put in place ( paid for ) by the government. Eventually public pays for through taxes.

Rail would be built and owned privately, access can not be denied, but the price charged for that access, correctly, could be steep.