> the claim is that other iPhones in the area are triggering the reboot
Lack of motion? The information the other phones provide are proximity (it’s unusual for people to pile their phones together), that the radios still work and possibly a timeline, e.g. if the other phone says “I’ve been in a suspicious state for two days,” the first phone can change its priors.
I could easily see this as a security measure. Give the phone a concept of fear of being stolen. Phone, alone, continued source of power for an extended period. Somebody could have left it on a charger and gone away. Phone, continued source of power for an extended period and static bluetooth signals from other phones--what's going on here? This is very suspicious, turn defenses to max. It doesn't need to know the difference between thieves trying to thwart it and cops trying to thwart it.
Lack of motion? The information the other phones provide are proximity (it’s unusual for people to pile their phones together), that the radios still work and possibly a timeline, e.g. if the other phone says “I’ve been in a suspicious state for two days,” the first phone can change its priors.