Conversely, emergency brake from the rear is better in an empty train since otherwise braking propagating from the front can cause run-in which can lift up empty wagons and derail them. Not good on curves.

The right attack could probably cause both the lead and rear to trigger a brake application.

Also, this assumes a pure air brake train - throw ECP in there and it will propagate the brake signal functionally instantly.

I do also wonder whether you could DoS it until the lead loco registers a comms loss and brakes thinking it's lost the last wagon.

If they want to cause real chaos, they should find a way to poke at the distributed power comms protocol. I've no idea whether that's similarly security-through-obscurity.