If it's not Teck that's doing the buying - well that was likely the problem to begin with (the price we're asking).
Except that if Teck opts for 75% but can't reach an agreement on the remaining 25% we are selling a vastly different project than we are now with so much uncertainty and this FS. If Teck were to take really any percentage then they will put the money into improving the FS and making this project worth a lot more than it seems to be worth right now. So really we should be asking for the improved project price from Teck now, because otherwise they would be doing the work for someone else.
Teck has to come up with a number that makes it more sensible to sell now with the uncertainty rather than wait until the end of the year for more certainty. Teck probably has a pretty good idea of what they would find since they've been drilling this property themselves.