I'm guessing that Orange's anti-Geass thingie-ma-bob basically undoes the affects of Geass. I remember that Lelouch couldn't use Geass twice on a subject but we see him tell Shirley to live after she was shot and her eyes get that glossy-red outline showing that the Geass "worked" on her.
Is this a mistake or did Orange fully take away Lelouch's use of Geass on her? If that's the case, think of all the benefits Lelouch can reap with Orange's ability--he'd be able to reuse Geass if he ever wanted to give someone a different order!