I can see where he is coming from, but surely such a policy would have an unacceptable risk of racism. Who is able to decide what is islamic radicalism? It would be utterly ahorrant to take a child into care just because you don't agree with the family's relgious beliefs.
www.bbc.co.uk/news/uk-26413024
Surely there can't be many fanatical muslim parents who are actually training their children up to be suicide bombers. Surely such radicalism is more likely to happen at university or in prison when the young person is lonely or vunerable.