I think by game breaking he meant "game ruining" as in ruining it for the person in prison who can't do anything.
Two thoughts.
1. Freeing prisoners by force.
Suppose you sack the enemy capital, you should have a chance to free all your imprisoned realm mates right?
2. Luxuries.
If the Judge is feeling generous, they can grant the imprisoned noble access to the academy. It gives the prisoner more to do during their stay and it can drive roleplay, maybe the Judge will try to flip the enemy noble in a stockholm syndrome type situation.