I don’t think it’s other iPhones that are sending a signal. Rather, it’s probably a security option that’s easy for most people to overlook in the Settings app.

I don’t think it’s other iPhones that are sending a signal. Rather, it’s probably a security option that’s easy for most people to overlook in the Settings app. I have little knowledge about iPhone hacking, but I think in the same place where you can say “delete my data after 10 failed passcode attempts”, you can also force ask for a passcode to start using accessories again if it’s been a long time since it’s been unlocked. But I don’t think I have ever seen anything around rebooting. That sounds like a very nice feature though since rebooting apparently is good for making sure the phone clears spyware access.