So shared meanings are defined by national boundaries and not by cultural/lingusitic ones?  Is there not a very overt nationalism or at least nation state bias in this approach?

Not necessarily. That example relates to political concepts, which are intimately tied to the nation/state, but the in group/ out group can be put together entirely differently.

For example, a religious group group can have an understanding of salvation that cross national borders, but is incomprehensible to people who aren't members of that religious group.  For example, predestination versus good works.  

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg