Meta, IMO that's exactly what an NDA is for. Non-disclosing. To not disclose whatever is going on.

Can you give any examples of news reports for other companies that have said "we're negotiating and considering being bought out" BEFORE an offer was firmly put on the table or even that they were in negotiations? Outside of hostile takeovers or where they put newreported "For sale" signs - and not just speculation and rumors? I can't, and I think for every one you can, you can also probably find 9 others that didn't.

The whole idea is, "We're interested in negotiating with you for the sale of your SC project, but we would like that to not be disclosed, and while we do our DD would require that this information be only available to us, or anyone else who signs an NDA". I honestly see no reason to say no, but I would put a clause about a timeframe on it. If we are in that case, we haven't gone so far out that it would suggest we didn't put a clause on. Again, working with Teck is probably in our best interest opposed to trying to somehow screw them.

Again - can you find any examples where they do disclose it in a similar situation? I think it's standard practice.