"service not available in au"
is that going to change sometime soon?
Can you use VPN in AU? Some countries restrict using VPN or TOR as far as I know, but I don't think Australia among those countries. I'm not encouraging you to gamble though, it's a risky thing and very unhealthy for some people. I'm just asking whether you can use VPN in Australia. )
I am pretty sure most countries on the planet can use VPNs. However keep in mind there is a legal issue. Say he wins $1,000,000 gambling on dice. How will he claim on his taxes where he got the money? He can't say Bitcoin gambling because its illegal in Australia.
He also can't say that he was on vacation in another country, gambled there and won because it goes by the personal primary residence.
Those are problems I'd like to have! ) To win $1,000,000 or other big amount in gambling is so rare that I don't think we should consider it as a potential problem. The most dangerous part of pursuing this goal is risking big amounts of money. Gamble responsibly, guys. Good luck!