It's because the market doesn't necessarily value everything in, or when it does the ability to move versus how much that movement is error/day to day movements.
Let's say SC is worth 800M and we have 400M shares (arbitrary #'s for easy calculations). We'd be worth $2, but the market isn't going to ever value that exactly - there's gonna be some margin of error. Depending on how bullish or bearish the market is, that margin of error increases.
Say in a fair market companies are valued 10% up or down of their true values. In bull markets they're valued up to 50% higher than their true values and the reverse for bear markets (again, arbitrary #'s).
Arizona was purchased for what, $2M? Let's say we do a RE and a PEA. For easy #'s lets say we get that up to 40M (again, easy #'s). That 40M is worth 10 cents in the SP but we're gonna have more in error so that 40M is never going to really be factored into the SP.
It's not that a rollback will change it, but the sale of SC makes it so that the value is now focused on Arizona, it's not just part of error. I understand that there's little in their hands now and that it's heavily in Teck's hands now. Can't just pay someone a six figure salary when he isn't doing anything because there is no longer any more work - so he should focus on something - but the vast majority of us don't want to be a part of Arizona, if we did want something so new and fresh there's a LOT of other companies that we could invest in for that. We want the pure play. Just the SC play. Everything else is wasted money in our eyes.