I don't think they are using a fake hand. It's just a pretty common way to have your hands ready for action. You can grap someone, or go for a draw very quickly. Also if you index your hands at the same spot all the time, it'll significantly speed up you draw.
When I was doing PSD stuff in Iraq we all stood like that with our hands not clasped, just in front of us. So we could grab a hajji, or go for a weapon quickly.
If you talk to a cop on the street, they'll often do the same thing.