I'd say that economic reality and sheer human greed impact discrimination as much as any other reason.  The Continental United States and Canada (an even more egregious example) could well afford to openly discriminate against and intern their Japanese American and Japanese Canadian populations because of the relatively small percentage of the population they represented.  Not so in Hawaii of the early 1940s where AJAs as labor were heavily represented in certain key industries, and whose wholesale incarceration would have spelled economic collapse during a time of war.  (It should be noted that in CONUS and Canada, Japanese immigrants had developed thriving farming and fishing businesses that were coveted by resentful "native sons."  It is disquieting even today to note how severe and permanent the demographic shift was due to internment.) 

Not to discount the role of men like John A. Burns, but in Hawaii the AJA experience was less traumatic during the war years because had to be.