Well no.
Mumsnet has rules, registering an account means ticking a box agreeing to abide by those rules. I'm sorry if you feel that is censorship, or a violation of your free speech.
Calling posters offensive slur terms and accusing them of being trolls just because you don't like that they disagree with you, is not allowed here. This is Feminist Chat, of course posters won't agree with defending an accused rapist.
You seem to be very upset that you've been "accused" of lots of things
That is a pretty normal human reaction to being called an offensive slur term for a mentally disabled person, a troll, a fascist, and all manner of other abuse.
you believe to be unfair but others believe to be true
Are you... are you trying to make the argument "but others believe that it's true that you're a [offensive slur term for a mentally disabled person] and a fascist troll so they should be allowed to call you that, even though it's against the site rules"?
Anyway I find it interesting that the poster who Advanced Search me and accused me of being a troll for posting under a new-ish username, accused me of attacking a "well-established longterm poster", yet the poster they referred to as "a well-established longterm poster" is also posting under a new-ish username.
I want to be clear I'm not troll hunting. Many Mumsnetters name-change frequently, using a username that doesn't have much of a posting history attached to it doesn't mean that one is new, or a troll. When I see someone posting from a new username, I certainly don't assume troll, I just assume it's someone who likes to namechange.
It's just quite funny that someone who called me a troll for posting under a new username refers to someone who's also under a new username as "a well-established longterm poster." What's good for the goose, eh?