The proper thing would have been to be upfront on the matter and reveal the true identity of the character as soon as Cumberbatch's casting was announced. This idiotic secrecy and mystery serves no purpose and ultimately won't amount to anything. Wehn future generations sit down to watch this movie, they'll know in advance who Harrison really is. Hell, as soon as advance pre-screenings begin the cat will be out of the bag and everyone will know. And even if somehow Abrams buys the secrecy of everyone there, the movie is set to be released on foreign markets before its American release. You can damn well bet Harrison's identity will be well known to every American as they walk in opening day.
So why stay silent about it now? Yeah, Abrams is a master manipulator who loves to jerk fans around and is probably laughing his ass off hearing about all the various fan theories. But from every rational and practical point of view there is no reason not to officially announce who the character really is.