Explain the problem as you see it
The move up/down shortcuts only move table rows if the cursor's in the leftmost column. In any other column, it tries to move the current node within the field. This makes sense when there are multiple nodes in the field, but the shortcuts do nothing otherwise.
Why is this a problem for you?
It makes working with tables clunkier and less intuitive.
Suggest a solution
I'd expect the shortcuts to move the current row unless there are multiple nodes in the current field.