Lail Shimurim or Lail Shomerai Negiah?

A school in Gurnee, IL apologized for scheduling a prom on Pesah night. The event will not be rescheduled since it's too late to do so.

I have mixed feelings about this. On the one hand, many students will be missing the seder to attend their prom. This is tragic. On the other hand, this may be a good thing: the more religious students (i.e. those who will attend the seder no matter what) will not be exposed to the promiscuity of a senior prom.