It's not just jobs. It's also relevant to US interests to keep industry skills sharp. Manufacturing insulin doesn't require the same skills that manufacturing a rocket requires.
On the flip side: if the skills are so expensive that private commercial entities are doing it for one or two orders of magnitude cheaper then it's arguable that the skills being paid to be kept sharp aren't really so sharp as they're paid to be. That is: at this price, why can't they deliver while private commercial entities can for cheaper?
So it's almost certainly just for the jobs and not really for the skills then.
The contractors making the SLS are private commercial entities. That's the mad thing about it.
Could be private commercial entities don't have to pay to train up the workforce but can just poach. Which is fine, system working as intended.
We complain about China brainwashing its citizens when the US is the OG offender.