The OP is 61 not 65 so he has some four years before any limitation on international flying in the immediate region would kick in. He makes the point that he would have been required to self fund the type rating, so the employer can't really claim any commercial penalty in employing him.
In any case, I thought that the jobs advertised were for domestic flying out of Sydney. If so, age would not be limiting.
Seems more like these guys don't want people with too much of a proper airline background. In which case, why not say something to the effect that preferred applicants should have recent time in GA because they want them to hump the bags, refuel and clean the cabin? There is no law against setting any practical requirements that the job may demand.
So blatantly playing the age card and compounding it with threats to blacklist with other operators demonstrates a very poor grip on how the game is played in these politically correct times.
As for the statement that he (or anyone) should retire gracefully, try telling that to the medical experts and governments who encourage us now to remain actively employed as long as possible. I know several pilots over 60 and two in their 70s who are sharper than some under 40 and who have more stamina when it comes to long duty days.