Seeing as I worked
here in a former life, I feel I might be a little qualified to chime in.
If New Zealand's immigration laws are anything like ours - and I suspect that they are, as the Commonwealth nations with socialized health care have pretty similar immigration law - this decision is neither unsurprising nor particularly out of the ordinary.
People can come to Canada on worker's visas, which are subject to a number of conditions and expire after a set amount of time; months or years, depending on the visa and case. Visitor workers staying beyond a set period of time are subject to medical evaluations because they become eligible for medical care after a certain period of residency. A visa does not guarantee future visas. That's the point - if you want to stay permanently, you have to apply for permanent residency.
What has probably occurred here is that the medical evaluations since he first moved to NZ have subsequently changed, and there are now stricter health standards. Because his visa appears to be a yearly matter, he is eligible for health care coverage. The 'burden' provision is a policy decision that evaluates health against known risk factors; he may have passed last time, but doesn't qualify any longer.
Here's the thing: the man is not a NZ citizen. He is not a permanent resident. He is a foreign worker. His status in NZ is legally temporary. He works on a visa. If he wanted to reside there permanently, he has had ample time to apply. He apparently has not. Therefore, his visa can be cancelled at any time for a variety of reasons, and its renewal can be denied for no reason whatsoever. If he was unhappy with that state of affairs, he should have sought to change his status. He didn't, and now NZ is perfectly within his legal rights to send him packing on whatever grounds they choose.
If you don't have a passport with the name of the country on it, or a
card with virtually the same rights, do not assume you have the right to live and stay in that country.
Perhaps having worked in a customs/immigration environment I have a more jaded view, but I am not in the slightest bit sympathetic to the man's plight. He had options, he didn't take them, and now he's being sent back to the country he has a legal right to reside in because he no longer has that status in NZ.