And from my reading, helps secure against a situation where an police officer (AKA attacker in the US apparently…) coerces you to unlock the phone (or perhaps even just takes it off you in a locked, but active state), and stores it in a faraday bag with a charger. They do that to keep it ‘alive’ so their experts can break in - a dead-mans reboot can help circumvent even that (as it will just reboot and restore itself to an encrypted rest state, which is much harder to attack)