The title of the article is the clue to its meaning, "Populate without perishing". Ziggy Switkowski, who was on Australian Prime Minister John Howard's nuclear power team, is writing for the Murdoch press, which is always spruiking for population growth. If you read carefully, Switkowski doesn't actually say that Oz's 21 millions (plus) are bad; he says what they do is important. (Fine political distinction usually used to promote or excuse more population growth).
Ziggy is alluding to climate change, but he is not, I think, talking down Australia's population, any more than is Frank Lowy, of the Lowy [Climate Change] Foundation.
Why do I say this?
There are a bunch of investors and developers out there who seem to be creating a ... um... climate ... where the idea of population growth and fuel depletion and climate change can be used to promote the need for nuclear power and therefore to promote investment in it.
That might be defensible on the face of it, since the Energy Returned Over Energy Invested (EROEI) of conventional nuclear has become relatively defensible with the the centrifugal separation of U235 from U238, if some very rich men, associations, and politicians did not seem to be relying on further driving up population numbers to enhance the chances of schemes for giant new nuclear-powered cities getting up. They intend to invest, not just in nuclear - and nuclear may simply be the flagship that will take a loss further on after they get out early with profits from land-speculation - but in big cities which they have managed to goad Australian governments to promise them. (An early document talked about somewhere between 50 and 150 huge new cities all around Australia.)
Continuous massive development schemes rely for funding on gambling on profits from continuous land speculation, but this is not possible if there is no project, however unsustainable, upon which further population and industrial growth can be pinned. Some big development speculators would be interested in the land and infrastructure associated with big new cities that population growth they have been promised by politicians (without agreement having been obtained from the community) will bring, far more than in investing in the power and plants themselves. They have been more or less guaranteed large dependent new cities to consume the nuclear power. They will make money on selling off land in advance and in floating schemes for other infrastructure - at least this is what they hope for.
Never mind that the nuclear power plants - at one $2bUSD plant per million or so Australians, just to provide per-capita electricity needs now  (not future expanded needs or replacement of fossil fuel) will probably never be achieved due to the financial cost of these plants and materials in a debt-ridden country in a debt-ridden world (where ultimately population and demand will fall in line with fossil-fuel). The gamble is that the promoters of these big city schemes will get away with funding the initial big ideas, leaving a host of unseen costs and unresolvable debt to smaller investors, and a gutted economic and political system for Australia with vast numbers of people in worse poverty than landless Mexicans, without a wealthy USA close-by to emigrate to.
In Australia the Australian Academy of Technology and Engineering Sciences (AATES) put together a document for a scheme like this a couple of years ago for government, with the collaboration of the Australian Multicultural Foundation. Note that Scanlon has also invested in tollways. Article and links to it below:
Scanlon report underpins threat to Australian democracy
Posted April 23rd, 2008 by Sheila Newman
What organisation has only 24 members of which the first ten comprise the current Prime Minister and nine past and present Australian Prime Ministers or Prime Ministerial contenders? And why would they be so dedicated to an organisation with a focus so antithetical to democracy and Australians? Read on.
 Figure based on French nuclear electric provision per capita in 2009 as provided by France 2 News covering provision of electricity during interruption to gas supplies from Russia and during severe cold spell. Note that Australians actually use more electricity per capita than the French and they also use more petroleum and more coal.]