There are prisons, of course. Every country has them. And some terrorists did get prosecuted and imprisoned. They weren’t hypothetical terrorists. Locals were getting stabbed, shot, run over, and bombed by them. So of course any non-radicalized Uyghur—which were the vast majority—wanted the terrorism to stop as much as anyone else, just as there were scarcely any US Muslims cheering as the Twin Towers fell. https://en.wikipedia.org/wiki/Terrorism_in_China#Chronology_of_major_events
But the job training facilities weren’t/aren’t prisons. Those who didn’t live near the schools traveled in for the week, received room & board, and went back home on weekends.