I don't suppose we'll know, but I bet there aren't any books featuring pigs in Jewish schools, either. Look, 99% of the kids are Muslim and, like Jews, all things porcine are proscribed by both religions (and the Jews shellfish as well, so no pork scratchings OR prawn crackers in their tuck shop). It's a pretty small gesture, isn't it, to withdraw the books from lessons? The books with pigs in them will remain in the library - they're just not going to feature them in class.
There's such an effort being made to whip up as much Islamophobia as possible at the moment, that something like this is bound to be fallen on by hysteria-makers, just like the shrieking about losing Britain's wonderful heritage when we couldn't say 'golliwog' any more, and Robertson's trimmed their jam logo to 'golly'. If you enjoyed being called a wog, you'd probably protest, too, but somehow I doubt that any of the niggers did.
It's just a small, local gesture showing some sensitivity for once: a bit more than we usually show when we go abroad to more conservative places and try to assert our 'right' to override local, national, or religious values because we're white Brits, and everybody's wrong but us.