Nonsense. There are people out there who have the goal "kill large numbers of people." Their motive is sometimes political, sometimes simply sociopathic... but the motive is irrelevant. If a fourteen year old boy can hack the train system and cause some minor damage (i.e. expensive train derailments) what could a motivated, fully grown adult do if they had that remote control instead? I suspect the answer is hundreds dead - maybe thousands with sufficient coordination and vulnerable systems.

A security hole like this is extremely dangerous due to the magnitude of its ignorance. Systems like mass transit should HAVE good engineers that spend time evaluating security risks and testing systems for robustness et cetera.

I doubt the hole would have been patched if someone called up their local Mass Transit Authority and said "Hey, uh, I've got this 0-day..." A 14 year old boy exploiting it, on the other hand, is probably going to draw some attention to it, and that attention will likely get the hole fixed, potentially saving hundreds of lives in the future.

If GM built a car that killed its inhabitants when a radio station played a certain song, GM would be to blame, not the radio station.