I think KGB Navy might be a better default. I'm not sure how much FPS action the game will have, since SC is mostly a flight sim game. If there is some FPS action, then Fleet Marines will be a good option for KGB members uninterested in a flight sim game who wouldn't otherwise play Star Citizen.

To the everlasting glory of the infantry...

Owain ab Arawn
KGB Supreme Knight
King's High Council