I can see how that phrasing would strike you as being redundant or inaccurate. To try to clarify --

The rocks not occupying the same point in space is a logical contradiction in the following sense: If it wasn't a logical contradiction, there wouldn't be anything preventing it. You might claim this is a "physical" contradiction or a contradiction of "reality", but I am attempting to identify this feature as a signature example of a sort of logic of reality.