That's all secondary to the overall point, which is that social security can be funded. It doesn't require this weird scheme where young workers pay into the system to support retirees, the US constantly prints money for all sorts of stupid shit and we could just print a few billion less for weapons. Besides, it's not like population growth is below replacement rates, because in addition to automation and taxes there's migration.

... well, there was migration. If the fascists succeed in ending migration, yeah, the US might have a demographic crisis.