Really? I would certainly hope these people have a much higher IQ than their complaints would suggest. Maybe these same people feel that McDonalds should have a menu option for Whoppers along with Big Mac's. Idiots.
Seriously, if they want Muslim symbols then go to a Muslim institution. However, they do not understand the whole "When in Rome do as the Romans". They expect us to adapt because their religion is so much superior (yes, that was sarcasm).
It's a private school. Assuming it doesn't receive government funding, I would say the there is a decent chance they don't have any legal standing. Depends on what laws are on the books to limit descrimination on the basis of religion with regards to private schools. I would wager that there isn't much there that the muslims could leverage.
That said, if the catholic school is accepting muslim students, I don't see the difficult with giving them a room to pray in. Of course, I don't think they're obligated to do so, but from a interfaith token of respect, it really wouldn't be that hard.
Eh. Put me down as not outraged in either direction.