Have you ever heard people say, when government policies transfer wealth from the young to the old, that it's because young voters have low voting rates while old voters have high voting rates?
If you believe politicians will naturally favour the interests of demographics who vote, then having equal voting rates across all demographics is required for a just society.
(Not that it's worked flawlessly for Australia, I'll admit)
The logical endgame of that approach is to have a big tug-of-war between two big coalitions struggling to steal stuff off the other (which, in fairness, is a pretty common equilibrium in democracies).
That actually goes right to the heart of the issue - you can't get a just society by doing things by the numbers. To get a just society, just policies need to be implemented. If the winning side of an election wants just policies then there will be a just society. Otherwise society will be injust. Participation doesn't change the dynamics of that at all - if anything it makes it harder because the majority is generally an unprincipled blob and certainly does not make time to reflect on matters of fairness (Australia is hardly a just society, simply that the people getting a bad deal are relatively small minorities, not actively mistreated and can be reasonably ignored). If we had a reliable process for achieving a just society we'd use that instead of democracy.
...why just two? He specifically mentioned advocating for ranked choice voting, which would make it a tug-of-war between N coalitions, and would lead to better outcomes that our current broken two-party system.
And if N coalitions playing tug-of-war, that means there is an (N-1)/N chance that your preferred one loses. It is much better if everyone agrees not to play that game and adopts smarter strategy. Which has little to do with the number of people participating in the election.
But it doesn't solve this particular issue.
The whole population is aging. Which means we're going to see higher and higher percentage of old people vs young people. Now what? We demand higher turnover rates from the young to cancel it out?
Either way, encouraging stupid people to participate is not the way. At best it is a harmless no-change manoeuvre.
If it’s not people who study policy as a hobby, then who ought to be voting?
Lot of great people of average intelligence. They should not be trying to involve themselves in governance. There should be no expectation or need that they get involved. Average people make poor decisions vs the unusually intelligent. Political discourse should elevate, not mean-regress.
The magic of voting is that most people vote for a side in a semi-random manner and cancel each other out harmlessly.