Yes, your edit exactly describes the behavior I had in mind. From the Ownership Manifesto,
Thus, while there is a scheme which allows independent access to different properties of the same aggregate value, it requires us to be using static enforcement for the aggregate access and to know that both properties are stored. This is an important special case, but it is just a special case. In all other cases, we must fall back on the general rule that an access to a property is also an access to the aggregate.
If x and y were instead computed properties of Point2D, the special case would not apply the code in the snippet would be rejected with an overlapping exclusive access error.