I don't think it's so much a fear, it's that there are many countries that operate Islamic courts already and people simply do not want that here. I'm one of them. I don't want any Islamic courts or any other religious courts in my country, even if it would only apply to them and it's not because i'm afraid of it, it's because it's fucking stupid.
If you think that it's only a "small minority" of Muslims who want Sharia law and Sharia courts, guess again. It's the vast majority. After all, these legal systems exist in most Islamic countries to some degree.
To think Sharia law is not being practiced already to some degree in large ex-pat Islamic communities would be incorrect. By the time Sharia courts are legally sanctioned, they would have already been using them behind closed doors for years. After all, a man recently married a 12 year old girl in NSW in an Islamic ceremony.
Edit: And people not wanting or liking something is the exact reason to protest it and for government intervention.
Honestly Jim, I'd be amazed if even half of what you've said is true with actual evidence to back it up.
Like with Malieus' claim about Sharia communities, there's a lot of bullshit out there passed off as fact and people are accepting it because they're suspicious or uncomfortable with these groups - in large part due to the government actively encouraging it.