You are right, there are no easy answers to these dilemmas. What I never can grasp, however, is how the same parents who turn their back on Christianity, and who often are the ones criticizing or showing open hostility to Christianity, are the ones who are anxious for their child to have the benefit of education in that environment. It seems to me that if homosexual parents kept to their own priciples, they would not choose to enroll their children in a Christian school. I do think one of the most compelling arguments is that the parents of other students have made a choice (and sacrifices) to ensure their children attend school in a specific moral environment. But the question as to how the school can show a "hate the sin, love the sinner" attitude really is a knotty one.
I am agree it is a tough call. Neither option seems ideal. But if you think that, apparently you become part of the agenda.