And there is your distinction that you are missing - the rock lacks CAPACITY for awareness. It doesn’t just lack awareness. It doesn’t have the capacity for it. That is something much more. You might argue that an infant lacks awareness, but you cannot say it does not have the capacity for it because as it develops, as we all know, it gains that capacity.
This is why my answer earlier was simply “because it is a rock”. A rock, by it’s nature, cannot be aware. No matter how old it gets or what someone does to it, it will never be aware. An infant, however, either has (arguable) or gains (not arguable) awareness at some point, so it does have the capacity for awareness.