Why do private member variables behaved like protected in the same module when creating deriving class?

[12345swordy]

Mike Parker told me that this is intentional and not a bug. 
However according to the spec: "Symbols with private visibility 
can only be accessed from within the same module. Private member 
functions are implicitly final and cannot be overridden."
Why private member variables behave like protected member 
variables in the same module? Can you explain your thought 
process when it comes to this design decision Walter Bright? Is 
there no way to mark the private member variables as "final" in 
the same module?

-Alex