Article notes this impacts soldiers (or I suppose others trying to be stealthy) who would have turned off bluetooth and wifi.
Can be harmful even without identifying information in situations where it's enough to decide if some building is occupied or not.
NFC however isn't touched by the airplane mode
...At least it was like that on the android phones I owned
On the Pixel 7, Airplane mode absolutely did not disable those frequency spikes upon screen unlock. Only disabling NFC through the dedicated setting in the phone’s parameters did (Settings > Connected devices > Connection Preferences > NFC). This theoretically puts Android users at greater risk, since on iOS, Airplane mode does disable those polling signals.
It’s easy to see how an average user might assume they’ve gone completely dark by enabling Airplane mode on an Android device—when in fact, they haven’t.
I’ll update the original post with this information, and thank you for pointing it out.