Unless he holds a rare qualification, endorsement or rating required in Australia, best he forget about a life Down Under - as it should be.
Tailwheel is correct.
Without wishing to sound xenophobic, the only pilots who might fit into this category are those involved in fire-fighting, who usually accompany the wet-leased aircraft that operate seasonally in Australia. Given the expertise required in these roles, I'd doubt that many of them are 30 or younger (and hence ineligible for 417 or 462 visas).
We need to be concerned when employers allege that a "rare qualification" is an endorsement (type rating now) on a type that is not dissimilar to other types already operating here. For example, if someone wanted to import and operate a Tupolev 204 here, the employer might argue that this is a "rare qualification" whereas in fact it is sufficiently similar to any other medium jet, and so there should be no justification for bringing in foreign workers.
DISCLAIMER : I know nothing about the Tupolev 204, nor do I anticipate there being anyone wanting to operate one in Australia..........but you never know!