"They are not insiders until they have been presented with the BFS. That hasn't happened yet."

The definition of "insiders" is quite broad:

Canada Business Corporations Act: Insider Trading

Introduction and Background

Insider trading has been described as the purchase or sale of a security of a corporation by an “insider” who has knowledge of confidential information about the corporation that might reasonably be expected to affect materially the value of its securities and that is not known by other security holders or the general public. The definition of an “insider” of a corporation is very broad, and varies depending on the context. It generally includes directors, officers, and significant shareholders of the corporation, as well as others who, in general, may have access to the corporation’s “inside” information. (Bold – mine)

Teck is closely involved with CUU on the BFS all along. They also would likely have other confidential, not yet public info that might affect the sp of CUU if it becomes public. They are also the party who might be making an offer for SC or CUU. They have to be "insiders" by definition and I doubt very much a company of their statute would risk buying quietly on the market and being accused of insider trading. JMO