I've heard of them about 10 years ago. Wasn't sure if it's true or not back then. Haven't looked in to it but it could be. I understand the U.S. had detention camps in WWII and am well aware of the concentration camps of Germany in the past. Some may have reasoned that to have them readily available in case of a crisis or something would be a good thing but just as likely to be used for not such a good thing.
Took a glance at your link. I may try to give it more of a read if I have time another day.
I am aware of these camps for some time now. Wouldn't surprise me if they're used for what they're being suspected. World conditions will only worsen, and deteriorate.
I've done a lot of reading and seen some documentaries about the holocaust. Very brutal. Some of the victims died after they were liberated and given food something to do with something like they were not used to eating that much or that rich of food. A lot of photos and commentary of the holocaust here: https://www.ushmm.org/#