"..He is probably unloading the +$2 shares he bought for tax loss reasons and then rebuying at today's prices..."

It may seem like a good idea, but the Income Tax Act does not allow that.

All the shares are pooled and the average cost is used as the "adjusted cost base" and when you sell, the cost of the shares you sell is based on this average cost. You cannot say the cost of this batch of shares I sold is the $2 shares I bought.