It's still a very good game with tons of bondage content and well worth playing – if you take it for what it is. Just don't expect it to be a direct sequel or the exact same thing Didnapper 1 was.
The heroes in this story do NOT abduct people, they only do it once (the priestess) and even that felt out-of-character for me and more like paying homage to the first game. A private prison wouldn't fit into the story concept at all. Only thing in this direction they could add would be to be able to do interrogation training with party members when camping but even that would feel like pure fanservice here (although I would welcome it non the less),