Since Hawaii was under military rule (martial law,) the Japanese presented less of a problem there. Also, relocating the large numbers of Japanese in Hawaii would have presented a much bigger logistical problem.
In wartime, it's enough for me -- and it was enough for the courts at the time -- that the relocations that were in fact practised should have had a rational basis. Much of the MAGIC intelligence is published in David D. Lowman, MAGIC. You can see from the evidence in that book that the relocation policy had a rational basis.
This is all something to bear in mind in our current situation.
Interesting that Chief Justice Rehnquist is apparently aware of the MAGIC evidence.
Not to mention the clearheaded, to the point and precise statements of Justices Stone, Black, and Rehnquist concerning the conventional and popular formulaic denunciations regularly levelled against Manzanar regarding threat assessment, race and specific sabotage indications.