Here's what I think:

According to the Agreement with Teck/CUU, Teck can opt to earn-back their 75% and have the choice whether to put the mine into production.

At the same time there exists an agreement with Liard that stipulates the mine has to be in production within 4 years of the Liard shares transferrring to Copper Fox. That suggests that Teck is bound by that timeframe since they will be earning back into that agreement and if they don't get that mine built, then Copper Fox will lose the Liard shares, and therefore so will Teck.

Also, rationally, if Teck is to spend $340 million they would want to put it to building that mine as fast as possible. There is very little reason for them to delay and put their money to no use.

At the same time, Copper Fox will be the operator while they earn back their shares and they will have to submit all their contracts for review, etc. just like we are doing now. While Teck is busy building that mine our value will be steadily increasing.

It only makes sense that Teck buy us out up front. I would assume with an external review it would be easier for them to arrange financing, and they would have a high degree of confidence in the project.