The single file comment refers to the bike lane. Law in Georgia states that bikes can ride two abreast.
As far as taking the lane, the law also says to ride as far to the right as is practical and safe. It is my judgement that it is more practical and safe when I'm traveling at 25mph to take the lane when cars have a whole other lane for themselves. I'm sorry you feel that it's wrong for me to do what I feel is the safest option in this situation, but the law, in this case, agrees that I can do what is the safest option for me and the cars sharing the road with me.
For 3 days, I get to part of a thousand other journeys.