Earlier quoted context omitted.
If only iPhones had a way to turn off its cellular radio, some kind of “airplane mode” or something
Why should we possibly believe that any software switches actually fully disable anything? If there isn't a hardware killswitch, there is no reasonable expectation that the cellular radio is actually disabled... There are trustworthy sources claiming that the NSA still tracks devices that are completely "powered off". No reason to believe that the CCP doesn't have that ability as well.
It can still communicate with towers even when phone is off. The phone can’t control that behavior.