Alot of this happened like the comic con and possibly the shooting of the empire cover and layout before he actually cut her. Im sure he didnt bring her into the movie just to cut but the scene she was in he said slowed down the pace of the movie. I dont quite understand why people are thinking Singer is trying to piss people off by cutting her. She was cut once they starting editing the film.
I know she was cut after the cover was arranged and the Comic Con appearance and the trailer. My point was that I don't think Singer is lying about cutting her in the hopes of surprising anyone, because after all that publicity it could hardly be a surprise. If he was concerned with wowing Rogue fans, he could have never told anyone she was involved to begin with.