Perhaps he's like a monk, cloistering himself and dedicating himself to mental self improvement.
If he's supporting himself and not taking substantial subsidies, then I don't care how long he studies, and he shouldn't be overcharged by the University.
That said, there should be a point, after successfully completing enough credits, where you graduate by default and receive your degree. After that, you are forced to pursue a different undergrad degree or join the masters track with all the appropriate tuition and responsibilities.