First, that comment you quote was specific to Ontario CANADA, not California. Second, I don't see where it says it was a Catholic School. Going by the name I would guess it isn't. Third, I said it was perfectly OK for the school to set a standard for the students it accepts, but the standard should be based on the THE STUDENT, not on the parent(s). How do you know this girl wasn't the one insisting on going to a Christian School, how do you know what she intended? You judge so much from knowing so little, I think Christ said something about that too...
The part of the story that's missing is what the daughter was saying to the other students at the game. Obviously this got the ball rolling. She could have been preaching to the other students that it was "ok" what her "parents" were doing. I could very easily see something like this concerning the school officials, and them investigating.