Your libertarian instincts seem pretty non-existent to me. Do you really think that jail is the best way to change minds? Or indeed that the jails are there to enforce anti-racist thinking? I can only guess that Tasmania is a much more enlightened place than London
The case for free speech – whether you agree with it or not – is not only (or even wholly) based on the rights of the speaker, but on the rights of all of us to judge for ourselves, not have the matter decided by a ‘higher authority’. If you take the view that the people are too daft to resist the appeal of foolish arguments, then clearly you should not be in favour of free speech. If, on the other hand, you are confident that foolish ideas can be combated by rational argument, then you should support it.