So many years later, there is a working patch to bring the behavior in-line with what you'd expect:
https://gitlab.gnome.org/GNOME/gnome-set...quests/322
Compiled gnome-settings-daemon 46.0 with the above patch on manjaro phosh (unstable branch) and can confirm it works exactly how you'd expect it to (you can individually disable any or all of the radios without airplane mode getting activated, while still being able to use airplane mode to turn off everything)
https://gitlab.gnome.org/GNOME/gnome-set...quests/322
Compiled gnome-settings-daemon 46.0 with the above patch on manjaro phosh (unstable branch) and can confirm it works exactly how you'd expect it to (you can individually disable any or all of the radios without airplane mode getting activated, while still being able to use airplane mode to turn off everything)