Yes, kill him. Ed Bouchette of the Pittsburgh Post-Gazette reported on Wednesday that Ben's injury is what will keep him out because it presents a danger of "pressing into his aorta" and ending his life.
This is not a normal rib injury, and it explains a couple things: one, why we heard words like "unusual" and "rare" when people described Roethlisberger's injury, and two, why he got the hell out of the stadium to see a doctor on Monday night. Smart move.
The injury is so rare, in fact, that doctors apparently told Roethlisberger they hadn't seen it since a rugby player dealt with the injury in 1989.