Of course, KWG and Cliffs do not want to be distracted by running a rail road but they do want to be assured of access and at a reasonable price. The only way you can obtain anything reasonably is if you are a partial owner. All businesses work for profit so these companies would rather that those profits were going into their pockets. That means that someone has to do the dirty work while they are a partner.
Yes I say generous because if the natives own and operate the rail line it will not be as the rail line was from Sault Saint Marie to Moosonee, i.e. barely making any profit. ( I think that rail line went bankrupt? Some of it must be operating because relatives of mine were on it a few years ago.)
The Ring's rail line would be sure to make profits and possibly huge ones for many years past the 20 when they take over. The Noront nickel and all the chomites are just a tip of a mineral berg in the Ring. This is going to be a big concern for this century.

Cheers.