Was in there a week ago for a work function and didn't know. A buddy and I went to the head at one point and he noticed me "adjusting". He carries semi-regularly and knew about the policy... "hey man, they've got a sign on the door"... "oh, really?"
So I went out and looked for the "sign" and it took me a minute. I usually look for a big red circle-X with a gun in it and this was just big white letters right in the middle of the door... I totally missed it until I left.
The fact that it's so big is clearly meant as [something more than] simply corporate following the suggestions of the lawyers. Somebody in BWW upper management is obviously very anti-gun and chose this course of action.