My parting message to this thread.
Op, I go with the mantra K.I.S.S. There's already a well established process to secure a US passport for people in your hubby's situation. Make an emergency appointment at a Passport Application Center to secure a passport. All the hail mary attempts people are proposing, just save that for extreme situations if you find yourself in one. Yes, as a USC you should not be restricted from coming home but why go a complicated route to get home when simple solutions are there. Good luck.
And I'm out.