It won't be permanent sequestration, though, or even necessarily long term. When these units are retired, their contained volume of CO2 will be reintroduced to the air, one way or another. In terms of scale, even several kgs of CO2 per person taken as a sum would still be a rounding error.

I suppose technically you are correct: a vanishingly small amount of CO2 is captured temporarily in units like these. It just doesn't matter for the issues where we need it to matter.

With current industrial processes, they usually will use some chemical reaction to create new CO2 because the can be certain of its purity. Most methods of capturing CO2 involve changing the chemical.