We have a nasty habit of creating scenarios where death is an inevitable consequence without it being the official policy.
This could be investigated further; was the average length of imprisonment less than a year, were the causes of death different than in the larger population, did economic conditions and racism increase the base death rate among Japanese-Americans in the first place, was the age distribution different among those the US bothered to move to camps, pushing their base rate lower?
Evidently people died because of these camps, and it is incredibly likely that many of those deaths were racist hate crimes committed by US employees on US citizens. Even that aside, it was very much wrong it imprison innocent civilians on the basis of their race. 'Thousands died' does seem like a substantial overstatement when the only number I can find is less than 2,000 (it's from the US, so it may be biased). Probably a few hundred died as a result of these camps, mostly from disease.
[1] - https://www.npr.org/sections/codeswitch/2017/02/21/516277507...
I'm not pedantically quibbling over whether it was 1980 or 2000 who died. I'm saying that if you took a random sample of 120,000 people at the beginning of 1943 and checked back at the end, 1,300-1,400 would have died. That leave hundreds, not thousands, who died in internment that wouldn't have died otherwise. These are arguable numbers, as I stated above, but they have more substance than I think you're implying.
Additionally, the US invested considerable resources into keeping these people alive. There were on-site hospitals, and not like the ones in Auschwitz where people were held until they died. These camps shouldn't have existed, but they were completely different animals from death camps and are not just a step away.
I’d be interested to know how many of the 120k were released. And of those who died, who many died “on parole.”
During the Gulf War (1992) the UK interned Iraqi citizens in the UK, just as they did with German citizens in WWII.
That was not a step away from mass murder.