I know I'm not Vette, but the way I've interpretted is that "it's been done" for a while but has been done poorly and upon review there have been a lot of mistakes and changes. So the reviews have take a long time because they've been making actual changes to the BFS during the review process, and changes to one section require changes to other sections as it's all interconnected. Basically they got a rough draft and had to make a lot of edits. Because of this, people have probably been hesitant to sign off as being in an envrionment of a lot of mistakes, you want to take even longer to look things over. In addition with it being generally complicated and your name being on the line.