It's an extremely accurate term, and using it in this context serves the purpose of not minimizing the importance of their being the sites of atrocities and internationally-decried human rights violations.
actually, it serves the purpose of riling people to action perfectly because it captures the scale and nature of the detainment centers at a time when information coming out of those centers is extremely limited and the state of a hearty share of the public rhetoric is that the people contained within the camps are subhuman.
the camps serve no productive purpose, yet here we are with a bunch of them in the country anyway.
If these people attempting to enter were simply turned around and immediately deported, the same people claiming that these are “actual in real life holocaust-2.0-about-to-happen concentration camps” would be upset about the “barbarism” of this stance instead of holding them while they wait for hearings.