a) Census admitted it provided block data ("This is an area where some Japanese-ancestry people live")
b) In 1942, Congress passed a war powers act that included a section repealing confidentiality for war purposes
c) Census did provide, in mid-1943 , some specific info on Japanese-ancestry people living in the DC area.
What do you have that is different or beyond that? ("4 days after Pearl Harbor . . . .")
Not a lot of details on my part. What we do know is enough: census race data was used to wrongly incarcerate not just one, but over one hundred thousand citizens. That’s reason enough for any President to refuse to run a census on any information beyond raw headcount, and for any citizen to refuse to provide any identifying/discriminating information beyond raw headcount.