I’m always amazed that these would-be terrorists survive being overpowered by the other passengers.
I'll second that, of course there's no concrete floors, brick, or metal. It's all tight quarters - plastic and upholstery. By grappling with him, you'd probably naturally wind up restraining him until he submits and is bound. I'd guess that an incidental death during a struggle most often occurs from either hitting your head or being choked. So, since there's not too much in the way of metal, brick, or concrete you smash a head against, unless they're choking him out they'd probably have to make a conscious decision to kill him there on the spot, and your average joe is probably content to just beat him until he's whimpering or not moving.