If the average person went on public transport, ranting and shouting at passengers, they would be ejected from the bus/train.
If the average person on their own, started yelling in Rundle Mall and accosting people, they would be warned and arrested if they didn't cease.
Quite why this group is allowed such free rein to "perform" as they do, impinging on the rights of people to walk the Mall/public places without being harrassed, is completely beyond me. The term "right to free speech" becomes a very convenient fallback for a percentage who actively abuse that right to the detriment of others who do not want their equal right to peace being impinged upon.