I think Tim is full of bs about doing it for realism. Usually if a firefighter es it won't be from a genetically altered virus that starts shutting down the body in 90 minutes. Do we really won't to go there i.e the rebar episode, the lightening strike. Athena landing a plane with no training and the help of a 12 year old make it make sense. I think that was a cold way to end Bobby. Bobby actually wanted to live finally after learning to forgive himself. And Athena though she loved Emmett and Michael, Bobby was her soul mate