You know you're about to die. And it's not a movie and you aren't a hero and all you can do is whimper and wait. This, now, was something we shared. I felt close to him. It wasn't compassion, just closeness. (The Ghost Soldier.154-6)
Tim forces the same knowledge on Jorgenson that he had to endure when Jorgenson freaked out instead of treating his wound. Once he's done that, once they've both felt the same fear of death, Tim is able to feel close to Jorgenson, and therefore accept him as part of the Alpha Company.