Bryan: That's what I assumed, but it seems a little risky. If the train happens to stop in the gap, for whatever reason, they'd have to send another locomotive out to push/pull it off the crossing. Very unlikely, but it could be annoying to the local drivers, and get the politicians' attention.
As for the ends of the rails, true, the SUV would have been hit anyway, and probably would have caught fire, But if it had been pushed onto the top of the third rail, rather than punctured by it, the wreck may not have been so bad. Or does Metro-North use underrunning third rail, making ramped ends impossible?