The blog links were failing whenever I clicked the links, I rechecked them and they look legit enough although I'm still somewhat dubious.
However the whole deal makes no sense, in the UK IIRC you have to be served in person and it has to go through the local justice area and again IIRC London has about 28. I imagine, the Australian system being based on the UK legal system, the courts would never even hear such a claim, especially from a US based company! It's actually a frivolous lawsuit, they purposely sued him in the wrong jurisdiction as a scare tactic.
Edit: The reason I feel it is false is not only because it's a US based company suing a UK citizen in Australia. But it's a defamation suit going through the Supreme Court, which in commonwealth countries is reserved for the most sever crimes (the high court is the appeals court). This means the case basically has to have a jury, defamation rarely has a jury.
The whole thing is false, my suspicion on the author is severely reduced (especially seeing where he's worked) but no legal firm in Australia would take on a frivolous case when both the prosecuting and defendant parties are both not based in the country.