Can't trust the guy with the whistle's views either it turns out. Is he just incompetent or is he corrupt? And you choose to believe the NRL has done their due diligence, I don't and my view is way more backed up in their history of corruptness than yours. Also, you are right, if he has been involved in match fixing / tampering, then he is liable for fraud but this assumes the authorities were reported to at the time and that we will never know.
Bearing in mind that the Australian government itself is now in bed with the NRL, it definitely isn't in their interests to pursue this either. The fact any ref can still be reffing after being involved in serious gambling issues in any sport is a joke.
And you thinking that the AFL guys is worse is just hyperbole and probably bias in favour of your preferred sport. The current AFL administration is tracking down toward the NRL's level is a huge concern for most of us AFL fans, so what they are doing these days is not a good thing to be comparable to even in a best case scenario.