Well, I don't know how this person managed it BUT they did in fact manage to mix and match costume parts to make 1 AMAZING outfit. I would highly suggest that if this is a glitch that it be investigated and turned into a default feature because it looks great.
Most militaries in the world do not permit one to mix and match uniform items with civilian attire. That being said, this is a game meant for the entertainment of the players. I would like the option to do so even if I never exercise it.