It might be time to ask why anyone thinks that nationalist and white nationalist mean the same thing. They do not. 
A nationalist is someone who loves and defends his or her country. A white nationalist is someone who wants to create a nation of whites only, so of course they are racists.
During the civil war the north was nationalist and fighting to keep the country together. The south was white nationalist and trying to break the country apart so they could continue keeping slaves as farm implements.