It is settled eclesiatical law that the church (and most churches) love the sinner but hate the sin. A good lawyer, or even a mediocre one could easily point out the conflict between the church teaching and the school rules since to infer homosexual activity is not necessarily reasonable. My point from the beginning of this conversation is that such a suit could be very interesting.
The lawyers who brought the case to the Supreme Court where slapped down like the simpletons that they are. The Constitution trumps local statute.