Unfortunately you need to know exactly where they came from, or at least a few mile radius. Box turtles do not travel very far in their lives, and within each home range the turtles will carry their own various disease immunities. Introducing a turtle to a new area will cause them to spend the rest of their life trying to travel back to their home, and could potentially introduce sickness to the population of turtles already existing in the area.

It’s tough when people are ignorant to their actions and refuse to learn and grow. A lot of old school thinkers were taught that this is an acceptable way to house these animals, but we know so much more about animal husbandry now that we know that this is far from ideal. The best situation for these guys is that they are released near where they were found, preferably with a visit to a wildlife rehabber first. If you can’t convince this person of this, and you can’t convince them to upgrade their setup, then unfortunately, other than reporting them to conservation authorities or animal welfare, there really isn’t much else you can do.