It's not for nukes. We have silos and submarines for those. It's for "responsive launch" and (skeptically) because the DoD has lots of money for space and not much idea what to do with it.
It's the Astra business model, hopefully without the Astra failure model.
(And practically speaking it's because you can't bootstrap a heavy lift launch company on VC funding or even a SPAC - the small sat launcher is a proof-of-concept for your medium/large launch vehicle).
On the site you can see: launch on demand, simple system that can go anywere, tactical launchs.
This is for nukes or similar stuff.