That's the point. Forcing them to move them would produce proof that the coins are active. And I would argue that to make supply and demand work (correctly) you need to know the supply.
I disagree.
1. Supply and demand works all by itself without intervention. In fact, intervention only creates problems. Just look at the dollar.
2. Knowing the number of spendable coins does not actually tell you enough about the supply. The "supply" is not a single value -- it is a curve, and knowing a single number doesn't tell you much about the curve.
3. We don't have a way to determine demand. Even if we did know the number of spendable coins, there is nothing we could do with that number.