"I guess free speech only works one way. "
it works both ways surely, anyone who feels FB has libeled or slandered them are free to purseue the same remedy he is through the courts.
"I would hope that most people with any level of intelligence would not be prepared to laugh at jokes about people with Down's syndrome, but no doubt that makes me humourless"
The point is the woman (if it's the one that I'm thinking of whos blog got made a lot of media outlets) went to the show, said she was looking forward to seeing him be more offensive, laughed at jokes at the expense of other groups which could be classed as vulnerable or in a minority but then took offence when a subject which was close to her personaly was targeted. So she doesn't really have a leg to stand on in terms of being morally offended.
Not an FB fan myself, but I don't think he's racist and tbf if a rag like the mirror called me a racist then I'd be suing them to.