Its about what is the correct thing to do.

In this case it is giving those parents an opportunity to take part in what they are already paying for.  A school that works.  If the school in their area does not, and they are paying attention long enough to notice, and would like to commit drive time and energy in re-enrolling where the kids have a chance, then why would we stop them?

The "unruly" argument is a legit concern, but the weight of responsibility and taxation without benefit would trump if ever challenged.