There is a thread in the Steam forum about the conditions of the Stars and Bars achievement. Looks like it is easy to miss and you only find out when it is already too late.
Based on what other players reported, I tried to edit my endgame save so that I would get the second promotion without playing all from start. What I did was this:
- savegame before activating the three warp projectors but with everything else done
- open the corresponding file "quicksave_xxxxxxxxxx.json" in Notepad++
- edited "morale" (line 509) to new value 32.xxx (was 22.xxxx)
- edited "gameTime" (line 511) to new value 991.xxx (was 99161.xxxx)
- edited "elapsedTime" (line 513) to new value 1019.xxx (was101966.xxxx)
- edited "difficulty" (line 514) to new value 32 (was 1)
- save the file (overwrite is OK, no need to rename for that purpose)
- load the save and activate the three warp projectors
- visit Kite Station and get your promotion

Hope this works for everyone.

EDIT: Sorry for typo in title. Just found out that you can go to Kite Station even without activating the warp projectors. Thought you have to finish a quest to trigger the dialog, but it's not needed.