Are you insane?
Apparentley there is no more freedom in opinion in Australia, and also no more freedom of speech.
You mistake freedom of speech with the reactions to that free speech. This confuses some people, who think that you can say anything you damn well please - like physical threats against politicians - and that everyone has to sit by and not react to that.
The problem of course is that the person making bizzare claims does not have the right to squelch the responses made to those claims. This is because everyone has the right - not just them.
And in the medical profession, there are laws, regulations, and guidelines they must adhere to.
We don't see many Christian Scientist doctors because their belief system precludes almost all medicines. In your imaginary loudest person wins world, a Christian scientist can be declared a medical doctor just by saying "I am a doctor, My medical training is complete and from the Holy Bible"
Sorry, but Anti-Vaxx is an opinion that is not backed up by facts, and has no place in a discipline based upon biology. It was created by a researcher in tandem with a lawyer who was trying to take advantage the almost inevitable guilty verdict that results when a child is involved against the medical profession. That's the reason that there aren't many medicines approved for pregnant women - too much liability exposure in all phases, from testing to administering.
So anti-vaxxing is a legitimate opinion, but neither valid, nor having a place in modern medicine. There are faith healing circus tent attractions to go to where that opinion is welcome. Otherwise we have to allow bloodletting and birth control by the woman drinking Mercury (ancient Chinese method)