That seems odd. Xstrata could put in a bid if they wanted anyway, regardless of whether or not the poison pill is in place. As quoted, "The purpose of the rights plan is [ignore] ... or to negotiate the terms of an offer with the board of directors of the Corporation."

I see this as more interesting (albeit confusing):

"a take-over bid made by an offeror who possesses confidential information concerning the Corporation [means that a bidder must enter into] into a confidentiality agreement containing a standstill provision with the Corporation within the three months that precedes the commencement of the bid."

I would think that this affects both Cliffs and Xstrata. Cliffs by virtue of their ownership position. Xstrata by virtue of being the processing lab on the current sample, which MIGHT qualify if the assayed results are considered material and substantial.

I'm not sure though, as SRP's are not something that I've seen often in the past in companies in which I worked or held shares.