Bounty,
Yes he has a ranch in Australia. Also 1 in Wyoming and vacation property at Lake Norris in Tennessee. He lives in Malibu. Should he choose to reside in Australia, so what? He spent his teenage and early adult years there and probably loves the place. There are literally 100's of 1000's of American expats around the globe and each chooses to do so for their own reasons.
I suspect that if Mr. Gibson only made films that he thought were politically acceptable he would not be nearly as wealthy or in demand. That's why they call it acting <img src="/images/graemlins/smile.gif" alt="" />
Ed