Yes, the bible does say that homosexuality is an abomination. However, there are many lessons in the bible that shouldn't be interpreted literally, or are no longer relevant today. For example, the bible gives us permission to sell our children. I would think that if one of these women tried to sell this girl, then that would be frowned upon, no?
Plaw, as for your example of the non-blind person wanting to go to a school for the blind, isn't that a sort of silly example. Since the major portion of what the students would be learning is how a blind person gets around in a seeing world, that's not a great example.
I feel that I've made my position quite clear. The school is discriminating and I don't believe that they have the right to do so. I was raised a Catholic and went to Catholic school for many years. I think that discrimination against anyone is so against what Jesus taught, that a Christian school should go out of its way to take in the lost lambs that might not be wanted elsewhere.