Surely somebody on that train had something in hand that could have been used to clobber the psycho. A briefcase, a laptop. A kick to the groin. Wimpx.
It says the train was CROWDED. Numbers alone indicate the other passengers could have overwhelmed the perp.
I bet they're all congratulating themselves for "surviving" the incident.
Easy to say but the thing is usually over by the time you've sorted out what's happening.