Ashley Manning is serving in the position as the official performing the duties of the assistant secretary. Michael Sulmeyer has been tapped to serve in the role once he's been confirmed by the Senate.
The Pentagon wants to make some of the Starship upper stage and the two-stage super heavy booster and Starship into government-owned, government-operated assets instead of contracting the company every time the rocket is needed according to Aviation
The absence of Austin would have no doubt exacerbated the alarm within an already trigger-happy U.S. military machine. Combined with those concerns is the lack of confidence in Biden's cognitive health as Commander-in-Chief.