"Anyone know the purpose of this challenge?"

My guess is that KWG does not want to give even one inch of space to Cliffs. Like Cliffs did coldly so many times with KWG, one of which being the 'NO' vote they registered in Montreal for the Special Shares Resolution sought after by Frank Smeenk a couple years ago...

KWG may also think that they need some more time for things to settle around the N/S corridor, and this appeal (if granted permission) will probably add some delay - until end of summer maybe. For some reasons, I have the feeling that the idea is kind of offside at this time within goverment circles, and not pushed very hard with Deloitte... The AGO intervention is probably perceived as hostile to KWG. Change in Queens Park may switch things in new directions perhaps...

GLTA.