[Chewbarkah]

Rebutting this claim ignores what really matters, which I’ll call the “Carry Ratio”. How many people are working to carry the entire population, including those who do not work, for whatever reason, in different time periods?

For starters, compare that ratio over time to see major trends.
The Aging of the population is a significant factor we can’t blame politicians for, directly (though it is why many of them support massive immigration to expand the base of the pyramid).
There will probably be a strong correlation to falling Carry Ratios and increased deficit spending by government.

More sophisticated research should get into how the trends bracket by demographic factors, the effects of earnings disparity (and how many earn enough to carry more than themselves), and whether those earnings are derived from wealth creation or government redistribution.

And what are the effects of investment, as opposed to wage income on the whole picture? The Leftist plan is to tap investment income to carry a large non-working population.

[Steve_Seattle]

"Rebutting this claim ignores what really matters, which I’ll call the “Carry Ratio”. How many people are working to carry the entire population, including those who do not work, for whatever reason, in different time periods?"

I (politely) emailed the author to make exactly that point. When conservatives cite the 90 million figure, it is not to claim that 90 million people are looking for work and can't find it, but that - as you say - a high-ratio of unemployed to employed is pretty much a guarantee of high taxes, large debt accumulation, and unfunded liabilities. It becomes harder and harder for the working population to "carry" the ever-increasing non-working population.