That is a lot of manpower that could be used elsewhere, were they actually a public service.

Immigration is their excuse to build up the security and internment apparatus. Building the prisons, the logistics routes, and training, radicalizing, and legitimizing armed goons takes time. Once the machine is running well, then they will turn it loose on everyone.

Can we free him?

Not without significant bloodshed and a high chance of failure. Which the person in question might not even want or agree to go along with.