"the American encampment in a higher ethnic concentration of Japanese" doesn't roll off the tongue quite as easily.
I'm not sure what the distinction is you're trying to make. That calling them 'interment camps' is somehow better than 'concentration camps'? Both words refer to holding a designated group of people, perceived to be a threat against their will without evidence or trial.
The distinction he is trying to make is quite clear... The term 'concentration camp' has a far greater negative connotation associated with it for glaringly obvious reasons...
I'm not sure what the distinction is you're trying to make. That calling them 'interment camps' is somehow better than 'concentration camps'? Both words refer to holding a designated group of people, perceived to be a threat against their will without evidence or trial.