It comes from EDV's ALPA arm showing where the 60 pilots they lost in August went. The interesting variation on a theme was that one of that 60 went to QANTAS.
I've worked with a few guys who have all flown in the US Regionals over the years. They were all Australian Citizens who had either married Americans or had American parents. You could also be a Green Card Holder I suppose and be able to work for a US Mainline/Regional Carrier then go to QF. I imagine the reciprocal arrangement would in be in place for a US Citizens