Antonio Kaufusi's story is quite humourous. He went to the Brothers Rugby Club thinking it was a Union outfit and listed his position as "Number 8" (keystone of the forwards, more or less).
I can only imagine the League coach staring at him and thinking, "Prop-forward. Yes. Yes, indeed..."
That said, as long as a player can demonstrate that they are substantially a citizen of the nation they want to represent, they should be allowed to do so. It's really up to them; certainly, Hazem el-Masri is international standard, but has chosen to represent Lebanon.
Karmichael Hunt and Antonio Kaufusi grew up in Australia, watching Origin and dreaming of pulling on the Maroon. That's pretty damn Australian, that right there. Personally, I give them even greater credit, because let's be honest here, it's much harder to make the Australian team than the New Zealand one. That's not to say that the Kiwis are inferior, just that they have a more limited pool to select from, so if you're a stand-out player it's more likely you'll be noticed and rewarded.
Honestly, I don't think it's a matter of Origin being seen as this, that, or the other. They just grew up Queenslanders, which is to say... Australian. They've made their choice.
By contrast, others like Brent Webb and so forth feel more Kiwi. More power to them; if that's where their heart lies, that's where they should play.