I understand the line of thought that if someone doesn't primarily identify as an Australian, the same applies for Queensland, as I understand that people fear the concept would turn into an All-stars series, but both of them are wrong imo.
Representing Australia and representing Queensland are two different things. State of Origin has NEVER been about who was born where, but about where you grew and developped as a football player. It is that rule of eligibility that counts, because that is exactly what Origin is all about, where your football Origins are, not your birth.
This. It's about what Origin means.
So many arguments start, so many possibilities are raised, so many hairs split, and real or apparent contradictions arise, and systems get rorted (for some at least) when one introduces "choice" into the equation. It should be as black and white (no pun intended) as possible.
As Porthoz says, and I agree: where you grew and developed as a football player is the Origin issue. Ethnicity is irrelevant.
Accordingly, if Benji Marshall qualifies for Qld under the above "eligibility rule", (which itself requires defining) he is eligible for Qld and not NSW. If he doesn't want to play Origin, that's a different matter. This is about eligibility, not a player's (or anyone else's) personal or economically driven preferences about wanting to play for NSW or Qld, eligibility, ethnicity or citizenship.
Equally, if Kasiano qualifies as per the above "eligibility rule" he is eligible for Qld Origin selection. And that should not, must not, be a bar to him representing his country (however that is defined) since national eligibility is an entirely different question to Origin eligibility.
The line has to be drawn somewhere, and for mine, this is the simplest, most rationally compelling way to explain the meaning of Origin, and the one least open to rorting.
As to identifying as a Qld'er for whatever reason, unless you qualify as per the above, it's irrelevant to your eligibility.