Given my own experience, I'd say that's an accurate concern.
The good news about handing prisoners over to the NDS vice directly to a prison system is that they actually have to go through a process of being investigated and being charged. If there is no charge to be laid, then they have to be released. So they're following a process of law, sometimes imperfectly, but they are following it. The risk of somebody being released from the system because they're not going to be charged is very high, and the documentation may not reflect that.