There’s not much of a public reason to create a Space Force National Guard. That couldn’t be handled by forming a new section of Military Reservists. As State Governments wouldn’t be in a position to ever use the formations in their Space Capacity.

Which means there’s likely something else going on. On the more unrealistic side of things. Maybe it’s a hint that we’re going to adding states. Except these would be based on Mars or something. Which would necessitate the creation of National Guard Formations. Sooner rather than later.

Alternatively. It’s a way of cutting costs and reducing strain on Federal Budgets. By Forcing the States to maintain National Guard Formations they’ll never have a reason to use. So the Feds don’t then need to add more units to the National Reserves they need to foot the bill for. Allowing them to use the New National Guard as an unofficial Space Force Reserve.