Biggles,
I naively thought that they were after people for the UK-Australia route, but the language priority seems to indicate a different route.
QF flights between the UK and Australia land in places where they speak Mandarin (Singapore), Cantonese (HK) and Thai (Bangkok). Clearly they will try to sell tickets to London in each of those markets.
That said (and without wanting to generalise), I would've thought most people in those markets who can afford an air ticket would be the educated ones who probably speak more than passing English anyway (thus rendering the language preference largely irrelevant)?
EU passport / UK ancestry permit would mean that the applicant could be employed in the UK, on UK conditions, without the employer having to bear the expense & time of sponsorship / transfer.
Re pilots - don't bet they haven't thought about it. However that would be EU crew, operating VH- aircraft on an Australian AOC which may raise other issues.