Mr Brown says if New Zealand continues its open-door immigration policy, the country could be inundated with people who have no intention of integrating into society.
Quite right. If immigration continues, we'll undoubtedly be "inundated" with more xenophobic bigots just like him, since such bigots can be found everywhere -- and their stench makes the whole world a lesser place -- but more importantly we'll also be "inundated" with good, hard-working people full of drive and enterprise, people who come here for a better life and who, by doing so, make this country a better place, despite the likes of Mr Brown and his party leader Winston Peters being in it.
UPDATE: It's true too that people "form their own mini-societies" just as Brown charges, but what his blind bigotry makes him unable to notice is that most "mini-societies" are made up of people who choose each other's company based not on race, but on the basis of shared values. People who like playing computer games, driving fast cars and talking philosophy for example will tend to spend a lot of time with other people who, respectively, like playing computer games, driving fast cars and talking philosophy.
That's a good thing. That's how a civilised society works.
And it's a good thing too that bigots like spending time with other bigots -- it saves us for the most part from being inflicted with their stench, except of course in election years.