In his editorial, Beattie argues his case for an adult game classification and retells of his experience at E3. I'm not going to retell his entire position here - you should head over and read it yourself - but he does mention that it's the South Australians holding up the process.
He also sums up my feelings on the matter quite well:
The argument from those opposed to an R18+ rating is that not having this classification will keep the nasty videos out of the country. How naive.
Head over to the Australian and read his editorial. And if you want some deeper analysis, check out Junglist's take on it at Kotaku.