Originally Posted by i_fly_AA

This makes sense to me. The point of the waiver is that UA is letting you change your flight for free despite the fact that your scheduled flight hasn't been cancelled yet. (If your flight gets cancelled, then you should get a free change, regardless of the new inventory.) If the new inventory is a higher fare, then you may wind up changing to it, your original flight could still go out as scheduled, and UA will lose potential revenue by giving up that higher inventory for free. Again, the point is that your scheduled flight hasn't been actually cancelled and the fact that UA is waiving advance purchase requirements as well as the change fee is generous.