The impetus to get the group back together is Dr. Saroyan's inability to determine if the body of a dead child belongs to a particular set of parents, supposedly due to her current team's inability to make the determination. All they had to do was run a DNA test, since they had the child and both parents available, to determine the issue. No explanation is given for why it wasn't done.
Booth continues to tell people he was an Army Ranger when it is obvious from his patches in this episode that, while in Afghanistan, he became a Green Beret. ("First Special Forces" patch and "Special Forces" tab on his left shoulder)