I doubt it was because it was a girls’ school – although I think he might have been less likely to say it in the first place if there were young muslim males in the class…

I think the most likely reason that they got shot of him out of the door as soon as possible was down to any potential negative reaction that this would have had from the less well-balanced muslims around the UK (and possibly the world, you know how these things spread), e.g. for precisely the reason that the comment was accurate.