Obviously I can't know events that occur in my future. The viewer's timeline is as out of sync with Song's as the Doctor's.
I figured the Centurion outfit was for Rory's sake, and Amy's. Morale. That was how Rory was dressed when he was at his very best. Strangely, it also helps him to fit in with the doctor's army. When going to war surrounded by old allies from throughout past and future history any one would feel like a right melon dressed in 21st century casual wear. And it makes a twisted sort of sense for Rory to wear it, since it is part of his story.
It's alternate costume Rory, that can only be unlocked by completing the first season of Eleventh Doctor Who. It's his alter-ego, superhero costume. It is worn strictly for Serious Business. And bedroom role-play.
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