I think the lack of photos is intentional. If I were him, I'd make sure everyone thinks I look a certain way and not give evidence of a variety of ways I could look.
He's also said repeatedly he wants the focus to be on his disclosures and the wrongdoing; NOT on him, how his girlfriend looks, etc. Using the same boring picture over-and-over is probably what he wants and appreciates.
On facial recognition: my understanding is that in addition to using data points that are relatively easy to change with makeup or surgery (cheekbone height, nose, etc), they use some that are not such as eyeball distance. However, could the eyeball based datapoints be tricked with specially crafted lenses in glasses frames?
But they could pass a law prohibiting the covering of your face like in France. "The French ban on face covering (...) is an act of parliament passed by the Senate of France on 14 September 2010, resulting in the ban on the wearing of face-covering headgear, including masks, helmets, balaclava, niqābs and other veils covering the face in public places, except under specified circumstances.
http://www.youtube.com/watch?v=k5H_b3mVz8s