My bad, I misinterpreted your response.
And I'm not saying faction loyalty is mandatory (MAG)
Quite easy to work around, my friend.
And I made my alts before they introduced 2 extra character slots for a monthly fee.
http://www.magleaderboards.com/view-player/Super-Pangolin
http://www.magleaderboards.com/view-player/Ghost-Pangolin
http://www.magleaderboards.com/view-player/Dedashi
Anyway, as far as I can tell you create the character (permanent details such as face, voice and tattoos) and this character has 2 different appearances - you can customize their clothing/apparel for play with both Security and Resistance... obviously the game will pick the appropriate set-up for whichever side's campaign you play in.