The seats in 1 A and K are only available for gold and premier card holders. They will be available for selection 72 hrs before the departure to everyone else.
I can testify from current experience that the second sentence is definitely not true. I am Silver and I flew in First from PHX on Saturday. I could not select 1K until T-24 despite it being available in the previous 48 hours.
If BA have indeed updated their seating policy with regard to OW Emeralds, it's pretty poor form that they haven't updated the website. However, the fact that YouFirst is wrong on the 72 hours bit leads me to keep an open mind on whether there really has been a change in policy.