This is a person who limits their diet to vegetables and kangaroo meat, on the grounds that kangaroos are not farmed. I find the subtleties of vegetarianism increasingly difficult to understand. The basic idea was that vegetarians refused to eat the flesh of animals that had been killed, so no meat or fish. The lacto-ovo-vegetarian allowed for the consumption of milk and eggs, which come from animals but don’t involve killing them. The pescatarian was a vegetarian who would eat fish. The reducetarian tried to cut down on meat and fish but did not entirely ban it from their diet. The flexitarian was essentially vegetarian but would eat meat and fish on occasion. These were the variations on the theme.
But increasingly the focus of vegetarians has become the wish to save animals from exploitation by humans, particularly because that exploitation often involves cruelty. This is combined with a desire to save the planet. So meat is still out because cattle are destructive of the environment in Australia and give off a lot of methane. There have been some shocking stories about the treatment of cattle but even routine practices, such as separating a calf from its mother, are seen as offensive. Milk and eggs are also out because taking milk from cows and eggs from hens is a form of exploitation. Likewise honey from bees.
So how to explain the kangatarian? Their argument is that kangaroos are not farmed but are plentiful in the wild. They can be killed humanely with a single shot. It is disappointing to discover that they produce as much methane as horses so there is no great gain for the environment in that respect in relying on kangaroo meat.
The coinage kangatarian was a humorous one originally, and was a bold statement of preference en environmental grounds for kangaroo meat over other meats available.
There is a brand of sausage called Kanga Bangas, which is nicely rhyming and colloquial, but the generally accepted term seems to be roo sausage.
The term kangatarian first appeared in 2010 and seems to have had some currency ever since. You may well have thought that it would disappear as a joke word for a food fad but kangatarians may be here to stay.