"Ma'am, I appreciate your concerns. Here at School X we strive in every way to further the best interests of our students and, of course, the school. We want the very best for your child, as well as for our adult employees, who are very much a part of the vibrant school community.
But she did nothing illegal, and we don't believe it's in anyone's best interests for her to be sacked - least of all hers. We are not a church school, and while we might hope to inculcate good moral values we do not have a puritanical agenda.
Among the values we would like our students to learn and live by is 'live and let live'. We do not encourage the imposition of elective, judgemental standards on anyone, our students or our employeers. We certainly don't wish to be seen to reward the student whose own lapse of judgement became a tool with which he could exert power over our staff. We will not give him satisfaction in that regard, whatever his motivation.
Again, please understand that I do appreciate your concerns. It is natural and proper to want what you believe is right for your child. But we have very many parents here, and very many ideas of what is right, some of which inevitably conflict.
In summary, then: get over it, you puritanical prude, and stop trying to use your children as a tool for your own petty power games. You are free to remove him or her from the school. Now get out of my office before I puke."