"To preserve the mission of our schools, and to respect the faith of wider Catholic community, we expect all families who enroll students to live in accord with Catholic teaching. Parents living in open discord with Catholic teaching in areas of faith and morals unfortunately choose by their actions to disqualify their children from enrollment."Instead of throwing tiny temper tantrums because we aren't a nation of robots who all think and speak in perfect tandem with their (or your) opinion perhaps people should take the time to learn the actual laws and rights in the US not to mention actual scripture they claim to quote.
In the US everyone has the right to believe what they want, say whatever they want about those beliefs, and live according to those beliefs. That means that a private institute can have their own moral clauses they required be they secular or religious based and those who CHOOSE to attend are required to follow them while they CHOOSE to attend. That is their right. If you don't like it then just imagine if it your beliefs were the ones being challenged instead for the same reason. It is the same for everyone and that is what makes it fair.
Now the people protesting are doing the exact same thing. They are "assuming" a double standard her but fail to catch that this is not someone being denied entry but re-entry, they were already a student here. There was no person interviewing on application saying are you (X). Instead there was, as there always is, a signed morality clause saying that the people will live up to (X) and when it is found they haven't they have the right to say sorry, no. They are also erroneously crying about God and Jesus but miss completely that that is exactly where the moral code, especially the one against homosexuality, comes from. It was God who said don't do it and it was Jesus who (yes, associated with sinners but then he...) called them to repentance. Never once did either say, "it's ok, do whatever you want" no they said "we will love you no matter what but you need to listen and obey." Thus the entire argument falls apart as a huge red herring. This is a private institute with a moral code that has been broken based on the teachings of their religion as they have the right under the law to have.
If you don't like it then go to a school that is secular but to demand that everyone change their view to agree with you because you are "right" and they are "wrong" just because that is what you believe is prejudice pure and simple not to mention persecuting someone for their beliefs which then creates hypocrisy on the part of anyone who is claiming that that should not be done. If you think they should be forced to take someone who is breaking their code of conduct just because you have no respect for their beliefs maybe you should take a good look in the mirror and then decide how you will feel when the person being being told what you can believe is you.