They didn't simply expel them, the sent them to a foreign prison. Don't misrepresent what occurred. And Kilmar Abrego Garcia is a legal resident. They are doing this to people who _do_ have the right to stay. Even for those who are in the US illegally, they are entitled to basic human rights and have protections under US law. They can be deported in accordance with domestic and international law.
Sending them to foreign prison camps instead is in fact a crime against humanity.