Rhinestone - This fundamentalist approach to Free Speech is out of step with pretty much all standard and legal precedents.
If I create a forum about Bananas for people to talk about Bananas then someone comes along saying "Bananas are SHIT! Apples are where it's at!" then I have every legal and moral right to ban them.
If they some along and say "The Labour party are rubbish", I have every legal and moral right to ban them.
If they come along and say "Yes Bananas are ACE, lets talk about them!", but I just don't like them, I have every legal and moral right to ban them.
Because it's my forum.
What I DON'T have a legal or moral right to do is to stop them setting up their OWN forums.
This is Mumsnat forum - they can set whatever rules they like. It is not a free speech issue.