Well, I don't like the way the mother has gone about it, and her reasoning does seem somewhat racist. But I really do think that parents and children should be free to opt out of some religious practices at school. Yes, I know the children in this story weren't worshipping in a mosque, but they were still visiting a place of worship.
We're Jewish, DD1 goes to local village CofE school, no other non-CofE schools in the area etc etc. At Christmas, the reception class were trundled off to the local church to take part in a carol service. I was horrified. To a Jew, to worship Jesus is blasphemy. DD1 is only 4, and while I asked her not to take part in prayers, it's all very confusing to her as she's obviously allowed to pray at synagogue.
So I asked for her to be excluded, and was told that either she had to go or I had to keep her home. In reception, that wouldn't mean truancy, but in any other year it would have. And I work, so I can't just randomly stay home with her because her school are going to church. I was absolutely furious about the whole business. I had to just ask her not to pray and hope for the best!