Re: I don't see how this is censorship
Ah, but in traditional harassment law, the penalties are applied to the harassor, not to the owner of the communication medium through which the harassing communication passes. This law is the equivalent of imposing a fine on the telephone company for not being able to prevent obscene voicemails from getting through.
As for how someone could use it for censorship: It's easy. Say you have a Facebook page I don't like. This law doesn't apply to it, but I file a complaint anyway. First several with Facebook (which will ignore them because I'm just being an ass) followed by one with the AU government that Facebook is ignoring it. Facebook then has to dig out its lawyers and audit logs and pay associated costs for an investigation (which finds nothing.) Technically they could sue me, but it's pretty easy to do all this from a false, untraceable identity.
So, I've just cost Facebook a few thousand dollars defending itself from a spurious allegation regarding your page.
Now I do it all again. And again. And again. With modern technology I can have a steady stream of complaints rolling in, possibly even from valid identities depending on how much I want to pay for it.
Facebook's reaction to these tactics in the past has been pretty consistent. Your page will be removed. They don't care about free speech. They won't continue to pay thousands of dollars a month in legal bills to stand up for you just on principle. Your page will be gone without my ever having to reveal who I am. And I can continue to use these tactics against you wherever you attempt to host your content next as long as they have some presence in Australia.
Plus there's the fact that the goal here isn't endgame censorship. The goal is to get the people to regard the government telling them what they can and can't post or read on the Internet as normal by starting with something that most people don't have a problem with. They'll come around for another nibble of your free speech next year.