Well, we know that national guidelines don't say to BF to six months, but I have been told that by medical professionals. TBH though, I think that when many don't BF at all, let alone to 6 months, to advise 6 months may seem a lot more achievable that to 12 months or more.
I think that Charlotte Church has done nothing wrong. She has BF for 6 months, which is more than most people do. And as for talking about the downsides, well, they do exist!