...reading the JV agreement I believe it states they need an updated FS as one of the documents for a production decision.
I don't believe it says that. It says the Management Committee may make a production decision based on ..... an approved Feasibility Study with such modifications, if any, as the Management Committee considers necessary or desirable."
There is already an "approved Feasibility Study" that was the basis of the JV. They can opt to make another one, or modify this one, but they don't have to for this Agreement.
Are you reading something else?
I should add, does it really matter if Teck wants to put this into production? I don't think anyone is going to stand in their way.