I think by "they" he meant "the Chinese" as a country, not the companies dealing with KWG. And that would presuppose that Baosteel has all the rights to Noront's production.

I know, it's a tenuous guess. But that's the only think that I think makes the question make sense. Or perhaps the reference was that if the Chinese "owned" a railway that was built (which is not the case, they'd finance and also potentially make a profit off construction) that they would be able to control shipping of all chromite from the Ring. That wouldn't be the case though, since the Chinese would not be the eventual operators of the railroad.

The end answer is that the Chinese will not be tying up all production of chromite from the Ring. They may secure some production streams, but not 100%.