So based on this, the safest place to sit is presumably the middle carriage?
I would actually sit in front now. Sometimes you would be able to still get vital information and being actually able to act. But the safe decision would be no to enter the train.
Optimistically assuming you have a minute to react (I'm imagining closer to 10s), what could one possibly do?
You might just as well never leave your bed, that's even safer ;) Train travel is much safer than travelling on roads, and in the same ballpark as commercial flight.